Long QT syndrome in children

Long QT syndrome is a disease that can cause syncope, seizures and sudden death. From June 1990 to June 1996, 11 children (male/female: 714; ages: 1 day-13 years with a median of 5.4 years) from different families were found to have long QT syndrome. Their corrected QT intervals (QTc) were 0.46-0.59 sec (median: 0.53 sec). All patients had normal hearing. One patient had Marfan syndrome with mitral valve prolapse. The presentation symptoms were: sudden death (2), seizures (6) and syncope (3). Their electrocardiogram abnormalities included: torsades de pointes (7), sinus bradycardia (4), T wave abnormalities (4), monomorphic ventricular tachycardia (2) and congenital complete atrioventricular block (1). All patients were treated with beta-blockers and one had pacemaker implantation. In a follow-up period of 0.5-6 years, 6 were symptom free, 1 died of ventricular tachycardia and 2 had recurrent syncope.

Cantrell's syndrome in an infant

Cantrell's syndrome is a rare combination of congenital midline thoracoabdominal defects and congenital heart disease. surgical repair can correct many of the anomalies. We report a neonate who presented with a short sternum, defective upper abdominal muscle, ectopic umbilicus, anterior diaphragmatic defect, ventricular septal defect and an intra-abdominal left ventricular diverticulum. Initially, the infant was treated with digoxin and diuretics for 5 months. Due to poor control of heart failure, one-stage surgical correction was performed with patch repair of the ventricular septal defect, ligation of left ventricular diverticulum and closure of the defects of the diaphragm and upper abdominal wall.

Cellular changes and induction of apoptosis in human promyelocytic HL-60 cells infected with the agent of human granulocytic ehrlichiosis (HGE)

Human granulocytic ehrlichiosis (HGE) is an emerging and occasionally fatal human infectious disease whose pathogenesis is largely unknown. Goodman et al. (1) recently described the successful cultivation of the HGE infectious agent in human promyelocytic HL-60 leukemic cells. It was reported in the same study that infectivity invariably led to host cell death, although the mechanism by which HGE infection triggers cellular self-destruction is as yet undetermined. In this communication, we show that in vitro passage of HGE pathogen-infected blood elicits a significantly dysfunctional G1-to-S transition. Moreover, we provide evidence that the cytopathic properties of the HGE pathogen are attributed to its ability to induce apoptosis in host HL-60 cells. Determination of specific protein expression changes by Western blot analysis showed that HGE infection resulted in reduced expression of PCNA and pRB, both of which play a role in cell cycling. Moreover, the steady state level of bcl-2, which protects eukaryotic cells against apoptosis, is suppressed by exposure to the HGE agent. These results suggest that this pathogen HGE induces apoptosis in HL-60 cells by a mechanism involving the shut-off of multiple cell cycle and apoptosis regulatory events.

Discovery of high affinity bombesin receptor subtype 3 agonists

Human bombesin receptor subtype 3 (BRS-3) was cloned based on its homology to the human gastrin-releasing peptide (GRP) receptor and neuromedin B (NMB) receptor. Some bombesin-like peptides were shown to activate BRS-3 expressed in Xenopus laevis oocytes, but only at relatively high concentrations, which suggests that BRS-3 is an orphan receptor. To study the pharmacology of BRS-3 in the context of a mammalian cell, we used BR2 cells, which are Balb/3T3 fibroblasts transfected with BRS-3 cDNA. A number of bombesin-like peptides found in mammals and amphibians stimulated calcium mobilization in BR2 cells but exhibited no effect on nontransfected parental Balb/3T3 cells. Of these peptides, NMB (EC50 approximately 1-10 microM) was the most active for stimulation of calcium mobilization. Testing of a series of NMB analogs truncated at the amino terminus and carboxyl terminus indicated that the minimal size of NMB required for retention of full activity was Ac-NMB(3-10). Systematically replacing each residue with alanine, or changing its chirality, demonstrated that the carboxyl-terminal residues His8, Phe9, and Met10 of NMB are important for optimal activity. We also tested whether a number of bombesin (BN) analogs that are potent pure or partial antagonists of the GRP receptor can activate BRS-3 in BR2 cells. One such analog, D-Phe6-BN(6-13) propyl amide, activated BRS-3-mediated calcium mobilization with an EC50 level of 84 nM. Through additional synthesis, we generated a significantly more potent analog, D-Phe6-Phe13-BN(6-13) propyl amide, which displayed an EC50 level of 5 nM for activation of BRS-3. Taken together, our data show that the core portions of bombesin-like peptides required for activation of BRS-3 are similar to those necessary for activation of the GRP and NMB receptors and thus provide pharmacological evidence that BRS-3 is in the BN receptor family. Furthermore, we have identified an agonist of BRS-3, namely D-Phe6-Phe13-BN(6-13) propyl amide, which is roughly 1000-fold more potent than BRS-3 agonists described previously.

Effects of microtubule inhibitors-taxol, vinblastine and estramustine on the growth and p53 gene expression in the hormone independent human prostatic JCA-1 cells

Treatment of the JCA-1 prostate cells with different concentrations of microtubule inhibitors-taxol (paclitaxel) vinblastine, and estramustine-was accompanied by reduced cell growth and, correspondingly, characteristic morphological changes. The reduction of cellular proliferation was unlikely to be attributable to an inhibitory effect of the antimicrotubule agents on cell cycling, but was correlated with the decreased expression of the p53 gene. These results suggest that antimicrotubule agents may be considered as potentially complementary treatment modalities for patients with hormonally independent prostate cancer.

Bombesin-like peptide receptor subtypes promote mitogenesis, which requires persistent receptor signaling

Bombesin-like peptides (BLPs) can regulate the growth of normal and transformed cells. To compare the relative activities of the three known human BLP receptor subtypes [i.e., the gastrin-releasing peptide (GRP) receptor, neuromedin B (NMB) receptor, or BLP receptor subtype 3] in growth regulation, we expressed each receptor in a receptor-deficient host, Balb/3T3 cells. None of the receptor agonists used in our study promoted DNA synthesis by quiescent parental, nontransfected Balb/3T3 cells. Using clones stably transfected with the NMB receptor however, we found that NMB stimulated the incorporation of [3H]thymidine 2.5- to 8-fold over basal levels. The greatest net stimulation of [3H]thymidine incorporation occurred when the medium contained insulin. In quiescent Balb/3T3 cells transfected with the GRP receptor, GRP promoted a 15-fold increase in DNA synthesis in the absence of insulin or other growth factors. GRP also induced the labeling of a large percentage (53%) of the cells with bromodeoxyuridine. To determine the length of time that GRP receptor signaling was required to drive quiescent cells into the S phase of the cell cycle, we blocked GRP receptor signaling by addition of a competitive GRP receptor antagonist at different times after stimulating cells with GRP. Our data demonstrate that persistent GRP receptor signaling throughout a large part of the G1 phase of the cell cycle is important in the mitogenic effects of GRP in these cells. Hitherto uncharacterized GRP receptor signaling pathways may be important in this process. BLPs also stimulated a mitogenic response by transfectants expressing the BLP receptor subtype 3 if insulin was contained in the medium. Taken together, these studies indicate that all three BLP receptor subtypes may contribute to growth regulation in vivo.

Pulmonary cavernous hemangiomatosis treated with interferon alfa-2a

Pulmonary hemangiomatosis is a rare, usually fatal disorder characterized by diffuse proliferation of blood vessels within the thorax. We describe a 7-year-old boy with cavernous-type pulmonary hemangiomatosis successfully treated with interferon alfa-2a. He presented with respiratory distress and hemoptysis that were alleviated during a 2-year follow-up period.

Phosphorylation of native and truncated isoforms of protein tau by the double-stranded DNA-dependent protein kinase (DNA-PK) shows that the primary phosphorylation sites are localized between amino acid residues 212-231 of the longest tau

Alzheimer's disease (AD) is pathologically characterized by the appearance of neurofibrillary tangles (NFT), senile plaques, and loss of subpopulation of neuronal cells. The NFT is composed of paired helical filaments (PHT) with extensively modified protein T as its primary constituent. Previously we had reported on the hyperphosphorylation of T by a double-stranded-DNA-stimulated protein kinase (DNA-PK). In this communication, we have compared the DNA-PK mediated phosphorylation of native and truncated TS with that catalyzed by the cAMP-dependent protein kinase (PKA). In addition, we have attempted to map the primary site(s) of phosphorylation of T by DNA-PK. Our results suggest that DNA-PK phosphorylates T at sites substantially different from those targeted by PKA. Furthermore, we show that the primary phosphorylation sites lie between amino acid residues 212-231 (using numbering system for the longest T, which is the isoform with four "repeats" and a 58 amino acid "insert" at the carboxyl- and amino-termini, respectively, of the protein molecule).

Late infantile type neuronal ceroid lipofuscinosis: report of one case

A 4-year-10-month-old boy with late infantile type neuronal ceroid lipofuscinosis was reported. He presented with progressive dementia, loss of visual acuity, gradual regression of speech and motor functions, and myoclonic jerks. A hyperactive deep tendon reflex was noted, but there was neither muscle weakness nor hepatomegaly. Serum lactate, pyruvate and ammonia levels were within normal limits. The funduscopic examination showed diffuse mottling of the retinal pigmented epithelium. The electroencephalogram showed irregular bilateral spike-and-waves or polyspike-and-waves and isolated focal spikes from the bilateral parieto-occipital regions. The wave forms of visual evoked potentials were flat. The electroretinogram was unrecordable. The somatosensory evoked potentials showed prolonged central conduction times from bilateral median nerves. The brainstem auditory evoked potentials were within normal limits. Diffuse cerebral and cerebellar atrophy were noted on magnetic resonance imaging. The diagnosis was confirmed by the electron-dense cytoplasmic inclusion bodies within the conjunctival squamous epithelial cells. No specific treatment was available. Regular anticonvulsants were not given during follow-up because seizures attacked him only on occasion. His visual acuity was progressively impaired. In addition to nearly total absence of speech, an inability to communicate and walk independently was also noted. The clinical features according to the subtypes, radiology, pathology, managements and prenatal diagnosis for this case are discussed.

Effects of IFN-beta and 1,25-dihydroxyvitamin D3 on cellular proliferation, induction of 2',5'-oligoadenylate (2-5A) synthetase and changes in immunoreactive pRB/p53 in human prostatic JCA-1 cells

The combined antimitogenic effects of IFN-beta and 1,25-dihydroxyvitamin D3 (vit. D3) were investigated by treating the androgen-independent JCA-1 cells, established from the primary prostatic tumor site prior to anti-hormonal therapy, with IFN-beta (1000 IU/ml), vit. D3 (100 nM), and both agents. Cell growth, changes in overall RNA and protein contents, and cell cycle regulatory proteins pRB/p53 were determined. After a 24 h exposure, a significant reduction in cell proliferation was observed in all three conditions. IFN-beta, vit D3, and their combination elicited, respectively, a 1.7-, 1.6- and 2.5-fold increase in total RNA and a corresponding 1.4-, 1.2- and 1.7-fold increase in soluble proteins. The IFN-inducible 2-5A synthetase activity was elevated by 15-, 1.4- and 21-fold, respectively. No differences in cell cycle phase distribution were found between control and treated samples. However, a significant change in pRB and p53 expression was observed upon exposure to these agents. A progressive increase in total pRB was observed in untreated JCA-1 cells, with the 48 h culture showing a 1.9-fold increase over the 6 h culture. The ratio of phosphorylated to the nonphosphorylated forms of pRB, however, decreased from 3.00 at 6 h to 1.2 at 48 h. The overall pRB increase as well as the modified:unmodified protein ratio change were both markedly decreased when the cells were treated with IFN-beta, vit. D3, or their combination. With p53, a similar progressive increase was also observed in control cells, which was largely abolished by IFN-beta but only partially blocked by vit. D3. The combination of IFN-beta and vit. D3 gave results similar to samples receiving vit. D3 alone suggesting that the effects of IFN-beta, insofar as p53 modulation is concerned, is distal to the effects of vit. D3.

Differential effects of retinoic acid (RA) and N-(4-hydroxyphenyl) retinamide (4-HPR) on cell growth, induction of differentiation, and changes in p34cdc2, Bcl-2, and actin expression in the human promyelocytic HL-60 leukemic cells

Incubation of the HL-60 cells with 3 microM of RA and 4-HPR resulted in suppression of cell growth and decrease in cell viability. A significant percentage of the RA-treated cells also displayed differentiation towards neutrophils, as assayed by changes in nitroblue tetrazolium reduction (NBT) and alpha-naphthyl-acetate esterase (ANAE) activities, whereas the 4-HPR treated cells remained essentially undifferentiated. Flow cytometric analysis showed 4-HPR to cause partial cell arrest in the G2/M phase after a 3-day treatment and an additional G1 phase arrest after a 7-day treatment. With RA-treated cells, a reduction in the percentage of cells in the G1 phase was observed after 7 days of treatment. In 4-HPR-treated cells an extra peak, characteristic of cells undergoing apoptosis, was found in the cell cycle phase distribution analysis. Determination of specific protein expression changes by Western blot analysis showed that the p34cdc2 was down-regulated by both chemicals. Furthermore, RA induced bcl-2 but prevented the processing of actin, whereas 4-HPR had little effect on bcl-2 but increased the specific processing of actin. These results suggest that RA promotes neutrophil differentiation and the establishment of a semi apoptosis-resistant state, possibly through the overexpression of the bcl-2 gene. By contrast, 4-HPR may trigger apoptosis by inducing overall cyto-architectural changes and specific DNA fragmentation subsequent to increased turnover of the protein actin.

Growth control of human prostatic cancer cells by the phorbol ester TPA: possible involvement of protein kinases

To gain insights into the involvement of kinases in the growth control of prostate carcinoma cells by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), immunoblot analysis and in vitro phosphorylation assays were performed using kinase discriminating effectors and extracts prepared from the androgen-dependent LNCaP and the androgen-independent JCA-1 human prostate cells. The down-regulation of PKC-alpha and -beta in JCA-1 cells was correlated with the effects of TPA. In LNCaP cells, proliferation may involve DNA-PK, proposed to act possibly via phosphorylation of the androgen receptor.

Isolated congenital left ventricular diverticulum

Congenital diverticulum of the left ventricle, a rare malformation, is usually associated with midline thoracoabdominal defect. We describe a case with congenital left ventricular diverticulum presenting as an isolated lesion. The lesion was suspected on two-dimensional echocardiography and was confirmed by cardiac catheterization and magnetic resonance imaging.

Control of renal carcinoma TC-1 growth, cyclin/kinase and nm23 expression by IFN-gamma and TGF-beta

To gain mechanistic insights into the growth control of renal cell carcinoma cells by IFN-gamma and TGF-beta, a recently established human renal carcinoma TC-1 cell line was treated with different concentrations of IFN-gamma and TGF-beta. Cell growth and changes in specific gene expression were evaluated. IFN-gamma exerted an antimitogenic effect on TC-1 cells, whereas TGF-beta was essentially without effect. The growth-suppressed cells had reduced expression of proliferating cell nuclear antigen (PCNA), the G2/M cell cycle transition regulatory proteins cyclin B/p34cdc2, the tumor suppressor gene pRB, and the antimetastatic gene nm23. However, levels of other cell cycle regulatory protein molecules such as cyclin D and p53 were unaffected by IFN-gamma. Thus, the antimitogenic effect of IFN-gamma may be mediated by its ability to modulate specific oncogene changes.

Regulation of growth, PSA/PAP and androgen receptor expression by 1 alpha,25-dihydroxyvitamin D3 in the androgen-dependent LNCaP cells

The involvement of vitamin D in prostate carcinogenesis was investigated using the human prostatic LNCaP cells. Incubation of the LNCaP with 100 nM 1 alpha,25-dihydroxyvitamin D3 for 2 days resulted in a 30-40% suppression of cell growth, which was accompanied by a greater than 70% down-regulated expression of the proliferating cell nuclear antigen (PCNA). The intracellular and secreted forms of PSA showed a 2-fold increase following a 48 h culture in the presence of vitamin D3. The vitamin D3-elicited PSA increases were preceded by an induction of androgen receptor (AR) expression, as measured by Western blot analysis and by binding assays using [3H]R1881 as the ligand. These results are consistent with the hypothesis that the growth inhibitory effects of vitamin D3 is partially mediated through its ability to modulate PCNA expression. Moreover, vitamin D3 may effect increases in PSA expression indirectly by up-regulating androgen receptors.

Specific cleavage of recombinant protein tau3 between valine-220 and tyrosine-221 (val-309 and tyr-310 of tau4) by a double-stranded DNA-stimulated protease

The protein tau was degraded to distinct products by a DNA-stimulated protease isolated from human leukemia HL-60 cell extracts. The enzyme partially purified by sequential chromatography on GTP-agarose, DEAE-cellulose, and TSK 3000 (0.6 X 60 mm) columns eluted as a 300-450 kDa protein which appeared as 60-90 kDa polypeptides on SDS-PAGE. Protease activity was stimulated by synthetic and natural DNAs and was most active at pH 8.5. Human recombinant tau3 was degraded by the DEAE-cellulose-eluted protease to a 26-kDa and several 14- to 16-kDa peptides. Degradation of tau was partially blocked by preincubation with tubulin, suggesting that the DNA-stimulated cleavage of tau occurred at the carboxyl-terminus, at or near the "tubulin-interactive" domains. The 26-kDa fragment was shown by amino acid sequencing to correspond to the N-terminus of tau whereas sequencing of the 16-kDa fragment yielded YKPVDLSKVT. These results show the existence of a DNA-stimulated protease capable of cleaving tau3 between valine-220 and tyrosine-221 (equivalent to valine 309 and tyrosine-310 of tau4).

Upper airway obstruction caused by vascular anomalies in children

Vascular ring or sling is one of the important etiologies for congenital upper airway obstruction in children. Between July 1988 and July 1995, a total of 92 children with stridor were initially evaluated by an esophagogram and two-dimensional echocardiogram. Seven children (7.7%) with variable types of vascular anomalies were diagnosed including pulmonary artery sling (2 cases), double aortic arch (1 case), right arch with left aberrant subclavian artery and ligamentum ductus (1 case), double aortic arch with one atretic arch (2 cases), and innominate artery compression of the trachea (1 case). The age at diagnosis ranged from 18 days to 3 years old. Only one patient was associated with an intracardiac anomaly. Five of the 7 patients were diagnosed as having laryngomalacia previously. Six patients had esophageal indentation on their esophagograms. Besides external airway compression, three patients also had intrinsic tracheal stenosis. Six patients received surgery because of severe respiratory distress. The patients' symptoms improved after surgery, but a premature baby died after a second operation for intrinsic tracheal stenosis at the age of 8 months.

One-stage repair of pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries by a handmade trifurcated valved conduit

An 18-year-old girl with pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries (MAPCAs) was reported. Her left-side pulmonary artery was absent, and the blood flow to the left lung was derived from two MAPCAs. One-stage correction, including the left-side thoracotomy and followed by the median sternotomy, was performed. A handmade trifurcated valved conduit was used to connect the right ventricle and the distal pulmonary arteries. The patient was doing well 3 years after the operation.

Gastrin-releasing peptide receptor signaling resulting in growth inhibition

We demonstrate that gastrin-releasing peptide (GRP) can inhibit the proliferation of human immortal nontumorigenic (184-B5) mammary epithelial cells ectopically expressing the human GRP receptor. Growth of Balb 3T3 cells ectopically expressing relatively high levels of the GRP receptor was also inhibited by GRP; however, growth of transfectants expressing lower levels of the receptor was not inhibited. Compared with Balb 3T3 cells, mammary epithelial cells could be rendered sensitive to growth inhibition by GRP by the expression of fewer GRP receptors. GRP also stimulated DNA synthesis in quiescent, serum-starved Balb 3T3 transfectants. In clones that were sensitive to growth inhibition by GRP by virtue of their expression of relatively high levels of the GRP receptor, the dose-response curve of GRP-stimulated DNA synthesis was bell shaped. This is consistent with our conclusion that the growth-inhibiting activity of GRP required the activation of a relatively large pool of receptors in Balb 3T3 cells. Significantly, prostaglandin H synthase inhibitors, which block the production of prostaglandins from arachidonic acid, reduced GRP-inhibitory effects on DNA synthesis. We also compared a number of GRP-stimulated signaling pathways in Balb 3T3 clones that were sensitive or insensitive to growth inhibition by GRP, including cAMP formation, phospholipase C activation, calcium mobilization, and arachidonic acid formation. Taken together, these results demonstrate a novel GRP receptor-coupled signal pathway promoting growth inhibition in which prostaglandin H synthase plays a significant role.

Summary of papers and research recommendations presented at the International Symposium on Lifestyle Factors and Human Lung Cancer, Guangzhou, China

This paper summarizes the themes and recommendations that emerged from the papers presented at the "International Symposium on Lifestyle Factors and Human Lung Cancer". In terms of our current knowledge, the following are considered important: (1) recognition and confirmation of lung cancer as a multifactorial disease; (2) the strong association known to exist between cigarette smoking and lung cancer does not explain the observation that the lung cancer death rate is lower than the smoking rate in certain groups of individuals, e.g. Chinese farmers; (3) the high incidence of adenocarcinoma in non-smoking women, e.g. Chinese housewives, suggests that factors other than cigarette smoking are involved for the development of lung cancer; (4) indoor air pollution is a significant risk factor for lung cancer in China; (5) there is incomplete information on the chemical nature and exposure assessment of indoor air pollutants; and (6) the need to better define the role of diet and nutrients as confounding factors for lung cancer. Based on the above, several recommendations were offered for continuing research to further our understanding of the etiology and pathogenesis of lung cancer.

An epidemiological study of risk factors for lung cancer in Guangzhou, China

Lung cancer has been on a rapid rise worldwide during the last three or four decades, in part due to modern social habits and unhealthy lifestyles. Although smoking, air pollution, and certain types of occupational exposure have been recognized as the major risk factors for lung cancer, the significance of each of these factors appears to vary with sex, country, and with region within a given country. In the case of nonsmoking females, some risk factors for lung cancer remain to be identified. In the city of Guangzhou, lung cancer is one of the five leading tumors and the rate has been increasing steadily in both males and females since the 1970s. In this report, more than 6000 cases of lung cancer deaths, accumulated over the past 9 years, were analyzed. The severity of air pollution and cigarette smoking were positively correlated with the incidence of lung cancer deaths. Analysis of levels of SO2 and NOx suggests that the major source of indoor air pollution came from cooking. Two studies were performed in order to determine the relative contribution and importance of smoking, indoor air pollution and occupational exposure as risk factors for the rising incidence of lung cancer. The first was a population-based case-control study involving 849 subjects (566 males and 283 females). The second study was based on the data made available by the Third National Census survey, in which the standardized mortality rate (SMR) and population attributable risk (PAR) for lung cancer due to occupational exposure for the population in Guangzhou were analyzed. Results of these two studies show that: in females, indoor air pollution, derived primarily from burning coal, was found to be a highly significant risk factor for lung cancer. In males, however, cigarette smoking and occupational exposure were significantly associated with lung cancer. To further elucidate the contribution of indoor air pollution as a risk factor for lung cancer in nonsmoking females, two additional case-control studies were performed in 1985 and 1986. The 1985 study involved 120 nonsmokers (28 males, 92 females) in which the influence of such lifestyle factors as: personal history of nonmalignant respiratory diseases, fresh vegetable consumption, lifetime occupation and occupational exposure histories, exposure to environmental tobacco smoke (ETS), degree of indoor air pollution, general conditions of home residence, cooking practices and environments, and family history of cancer were first individually assessed and then collectively subjected to multiple conditional regression analysis for evaluation as risk factors for lung cancer. The 1986 study involved 75 cases of never-smoking females in which the aim was to investigate the influence of exposure to spousal smoke as a risk factor for lung cancer. These studies suggest that consumption of fresh vegetables was a "protective" factor for lung cancer in both males and females. In females, indoor air pollution and size of the kitchen were risk factors for lung cancer, whereas ETS exposure, respiratory disease history, family history of cancer, living conditions, use of cooking fuel, and participation in cooking, were not statistically associated with female lung cancer deaths. Occupational exposure was also correlated with the incidence of female lung cancer deaths. In males, chemists had the highest SMR, whereas in females, homemakers had the highest SMR. In males, the most common lung cancer cell type was squamous cell carcinoma, whereas in females adenocarcinoma was the most predominant type. The factors affecting the distribution of histologic lung cancer cell types were also investigated and discussed.

Specific processing of native and phosphorylated tau protein by proteases

Protein tau is a group of developmentally regulated proteins with implications in the pathogenesis of Alzheimer's disease (AD). To study whether phosphorylation of tau by different protein kinases may affect subsequent reactivity to proteases, human recombinant tau-3 was phosphorylated with PKA or a double-stranded DNA-dependent protein kinase (referred to as DNA-PK), followed by incubation with thrombin or a double-stranded DNA (dsDNA)-stimulated protease. Quantitative degradation of tau was measured by the disappearance of the substrates or the appearance of products on SDS-PAGE. With thrombin, tau-3 phosphorylated by DNA-PK was degraded faster than the native protein which was processed at a faster rate than tau-3 phosphorylated by PKA. With the dsDNA-stimulated protease, however, tau-3 phosphorylated by PKA was processed faster than that phosphorylated by DNA-PK. Thrombin-mediated degradation of DNA-PK phosphorylated tau-3 gave a pattern different from that using the native or the PKA phosphorylated tau-3 as substrates. These results suggest that the rate and/or sequence of phosphorylation at specific sites of tau may provide "micro-environments" and/or conformations which alter their accessibility and/or reactivity to proteases.

Envelope gene sequences of human T-lymphotropic virus type 1 in Taiwan

Three major types of HTLV-1 had been proposed, the Melanesian type, the Zairian type, and the cosmopolitan type, which was further divided into subtypes A, B and C, according to the phylogenetic tree constructed from LTR sequences of current HTLV-isolates. In this study, the envelope gene sequences of HTLV-1 from 9 Taiwanese were analyzed. Based on the phylogenetic tree constructed by unweighted pair group method and the sequence homology analysis by GCG computer programs, the envelope gene sequences of HTLV-1 proviruses from these 9 Taiwanese belonged to subtype A or subtype B of the cosmopolitan type and were closely related to HTLV-1 from Japan. Twelve subtype-specific nucleotide variations were deduced from the comparison of complete or partial envelope gene sequences of 16 HTLV-1 isolates of known subtypes as well as those of 9 Taiwanese. These data provided the basis for subtyping the cosmopolitan type of HTLV-1 by amplification of envelope gene sequences and restriction fragment length polymorphism studies. A more extensive survey based upon this proposal was warranted.

Modified Senning procedures for simple transposition of the great arteries

From December 1990 to July 1994, 10 infants with simple transposition of the great arteries (TGA) underwent the Senning procedure at National Cheng Kung University Medical College. Their ages ranged from 1 to 8 months (mean, 4.8 +/- 2 months), and their body weight ranged from 3.5 to 7.5 kg (mean, 5.7 +/- 1.2 kg). Four infants were treated with the conventional method by covering the sinoatrial (SA) node with the anterior right atrial flap (group 1). The other six patients had modified procedures, having the suture line across the caval vein, caudal to the SA node (group 2). Three of the group 1 patients experienced junctional rhythm temporarily, another had SA node dysfunction for 1 week postoperatively. In group 2, all patients were in sinus rhythm except one, who returned to sinus rhythm on the second postoperative day. There was one (10%) surgical mortality, a patient in group 1, and one (10%) late mortality, in group 2. The clinical follow-up interval was 6 to 46 months (mean, 28.8 mo). All survivors were in sinus rhythm, and echocardiographic studies demonstrated no difference between the two groups as to conduit obstruction or degree of tricuspid valve regurgitation. In conclusion, in situations that require atrial switch for the correction of TGA, a suture line across the caval vein, caudal to the SA node, may be a useful modification to prevent arrhythmias.

Changes in cell growth, cyclin/kinase, endogenous phosphoproteins and nm23 gene expression in human prostatic JCA-1 cells treated with modified citrus pectin

Modified citrus pectin (MCP) added to the media of cultured androgen-independent human prostatic JCA-1 cells reduced cell growth and correspondingly [3H]thymidine incorporation into DNA, which was correlated with the down-regulation of cyclin B and p34cdc2 MCP also induced distinct increases in specific endogenous phosphoproteins, including a cAMP-stimulated 52,000 (52-kDa) protein. Since metastatis has been inversely correlated with nm23 gene expression in some cancer cells and was reportedly inhibited by MCP in a rat prostate model, we investigated steady state level changes in the nm23 protein in JCA-1 cells and found it to be unexpectedly suppressed as a result of exposure to MCP.