Growth hormone and insulin-like growth factor-I and mesangial matrix in uremic rats

Combined growth hormone (GH) and insulin-like growth factor-I (IGF-I) therapy has been advocated for clinical use to minimize the diabetogenic effect of GH and enhance their anabolic effects. However, GH has been shown to accelerate the development of glomerular sclerosis in experimental animals and IGF-I mediates the renal effects of GH. The purpose of this study was therefore to examine morphometrically the effects of GH (1 mg intraperitoneally three times a week), IGF-I (50 micrograms/kg body weight subcutaneously twice a day), and combined GH/IGF-I treatments in vivo on mesangial matrix at 3-20 days after 5/6 nephrectomy in 140- to 150-g rats. There were no significant changes in growth and renal function after GH and/or IGF-I treatment. The effects of GH and IGF-I on glomerular size were additive, which were more prominent in juxtamedullary glomeruli. GH induced proportional increases in mesangial area (MA) and glomerular area (GA), whereas IGF-I induced a similar increase in GA without a corresponding change in MA. When compared with GH treatment alone, combined GH/ IGF-I treatment resulted in a lesser degree of mesangial expansion despite an enhanced glomerular size. While additional studies are needed to examine the long-term effects of these findings, our results suggest a potentially beneficial effect of combined GH/IGF-I therapy during uremia.

A high molecular mass non-muscle tropomyosin isoform stimulates retrograde organelle transport

Although non-muscle tropomyosins (TM) have been implicated in various cellular functions, such as stabilization of actin filaments and possibly regulation of organelle transport, their physiological role is still poorly understood. We have probed the role of a high molecular mass isoform of human fibroblast TM, hTM3, in regulating organelle transport by microinjecting an excess amount of bacterially-expressed protein into normal rat kidney (NRK) epithelial cells. The microinjection induced the dramatic retrograde translocation of organelles into the perinuclear area. Microinjection of hTM5, a low molecular mass isoform had no effect on organelle distribution. Fluorescent staining indicated that hTM3 injection stimulated the retrograde movement of both mitochondria and lysosomes. Moreover, both myosin I and cytoplasmic dynein were found to redistribute with the translocated organelles to the perinuclear area, indicating that these organelles were able to move along both microtubules and actin filaments. The involvement of microtubules was further suggested by the partial inhibition of hTM3-induced organelle movement by the microtubule-depolymerizing drug nocodazole. Our results, along with previous genetic and antibody microinjection studies, suggest that hTM3 may be involved in the regulation of organelle transport.

Down regulation of bcl-2 by p53 in nasopharyngeal carcinoma and lack of detection of its specific t(14;18) chromosomal translocation in fixed tissues

High levels of bcl-2 protein have been found in a wide variety of human cancers. Since p53 gene inactivation occurs in over half of human cancers, it is possible that loss of p53-mediated repression of bcl-2 gene expression accounts, at least in part, for the frequent abnormalities in bcl-2 protein production seen in tumours. By using immunohistochemical methods, we have analysed thirty-three nasopharyngeal carcinomas for p53 and bcl-2 expression. We found an inverse correlation between the expression of these two proteins (P < 0.001). Moreover, we utilized universal oligonucleotide primers of a region 5' to the bcl-2 MBR and at the 3' end of JH segments to initiate a DNA polymerase chain reaction that amplified these bcl-2-JH junctures. Of the twelve nasopharyngeal carcinomas expressing bcl-2, none showed a t(14;18) chromosome translocation. These findings may indicate potential mechanisms by which bcl-2 regulates apoptosis.

Qualitative and quantitative strategies of thermal adaptation of grass carp (Ctenopharyngodon idella) cytoplasmic malate dehydrogenases

Malate dehydrogenase isozymes of grass carp,Ctenopharyngodon idella, were identified by mitochondrial preparation and thermal denaturation. The structural and kinetic characteristics of chromatographically separated thermostable and thermolabile cMDHs were different in (1) half-life at 42°C, 10 min and 24 h, respectively, (2) optimal substrate, oxaloacetate and malate, concentrations, and (3) the apparent Michaelis-Menten constants of NADH and oxaloacetate.Total MDH activity in white muscle of 11°C-acclimated fish was about twice that of the 30°C-acclimated group. In addition, the ratio of the thermostable to thermolabile cMDH activity in white muscle of 30°C-acclimated fish was significantly higher than that of 11°C-acclimated fish. These results suggest that temperature acclimation can induce temperature compensation in MDH activity and differential expression of thermostable and thermolabile cMDH isozymes in freshwater fish.

Differential displaying of mRNAs from the atrioventricular region of developing chicken hearts at stages 15 and 21

In an effort to isolate novel genes that may be involved in the development of the cardiac cushions and then the formation of cardiac valves and septa, we utilized the differential mRNA display method in conjunction with the whole-mount in situ hybridization. The total RNAs used to differentially display were prepared from atrioventricular (AV) canal regions of stage 15 and stage 21 chicken hearts because critical events known to be important for the AV valve and septum formation occur during this period of the development. We have successfully obtained 14 potential candidate genes. Three examples, 15H16 (phospholamban), E13 (skeletal alpha-tropomyosin) and 21C (a novel gene), are discussed here. Levels of mRNA expression in developing hearts were determined by Northern blot analysis and their expression patterns were revealed and compared using whole-mount in situ hybridization. Both phospholamban and skeletal alpha-tropomyosin messages in the myocardium of the AV canal region showed significant decrease during this period of the development. The 21C differential display product detects a novel 9.5 Kb message whose expression is cardiac-specific at early stages of development. The expression level of the 21C gene appeared to be increased from stage 15 to stages 21 and 25 as determined by both Northern blot analysis and in situ hybridization. From these data, we demonstrate that the differential display method together with the whole-mount in situ hybridization could be an effective means for the isolation of novel and differentially expressed genes.

Overexpression of microfilament-stabilizing human caldesmon fragment, CaD39, affects cell attachment, spreading, and cytokinesis

Previous studies have demonstrated that overexpression of the carboxyl-terminal fragment, CaD39, of human fibroblast caldesmon in Chinese hamster ovary cells protected endogenous tropomyosin from turnover and stabilized actin microfilament bundles [Warren et al., 1994: J. Cell Biol. 125:359-368]. To assess the consequences of having CaD39-stabilized microfilaments in living cell, we characterized the motile behaviors of stable CaD39-expressing lines. We here found that CaD39-expressing cells adhered faster to plastic, glass, fibronectin-coated glass, and collagen-coated glass than control cells. Moreover, the CaD39-expressing cells also exhibited enhanced spreading immediately after attachment. Despite these differences, overexpression of CaD39 had little effect on the velocity of intracellular granule movement, or the velocity and persistence of cellular translocation. However, CaD39-expressing cells were more elongate and encompassed less area than non-expressing cells during migration in a wound-healing assay. In interphase cells, the expressed CaD39 fragments were found associated with tropomyosin-enriched microfilaments. Like endogenous caldesmon, the CaD39 fragment was also modified at mitosis. Although a significant portion of CaD39 underwent only partial modification, the majority of the CaD39 was released from the microfilaments during mitosis. This is consistent with the finding that the CaD39-induced advantage for attachment and spreading was lost during mitosis. In CaD39-expressing cells, an incomplete release of the CaD39 from microfilaments at mitosis was found which may be responsible for the increase in the frequency of multinuclear cells in CaD39-expressing lines.

Subtraction hybridization identifies a novel melanoma differentiation associated gene, mda-7, modulated during human melanoma differentiation, growth and progression

Cultured human melanoma cells lose proliferative capacity and terminally differentiate after treatment with the combination of recombinant human fibroblast interferon (IFN-beta) and mezerein (MEZ). Subtraction hybridization of cDNA libraries prepared from actively proliferating human H0-1 melanoma cells from cDNA libraries produced from H0-1 cells treated with IFN-beta + MEZ identifies a novel melanoma differentiation-associated (mda) cDNA, mda-7, that displays elevated expression in differentiation inducer-treated H0-1 cells. mda-7 encodes a novel protein of 206 amino acids with a predicted size of 23.8 kDa. The level of mda-7 mRNA is elevated in actively proliferating normal human melanocytes versus primary and metastatic human melanomas. In the Matrigel-assisted melanoma progression model, mda-7 expression decreases in early vertical growth phase primary human melanoma cells selected for autonomous or enhanced tumor formation in nude mice. Treatment of human melanomas with IFN-beta + MEZ, and to a lesser extent with MEZ, results in growth suppression and induced or enhanced mda-7 expression. Immunoprecipitation analyses using peptide-derived rabbit polyclonal antibodies detect increases in mda-7 protein, and a higher molecular weight protein of approximately 90 to 100 kDa, in MEZ and IFN-beta + MEZ treated H0-1 cells. mda-7 is a highly conserved gene with an homologous sequence in the genome of yeast. Transfection of mda-7 expression constructs into H0-1 and C8161 human melanoma cells reduces growth and inhibits colony formation. These results confirm that mda-7 has antiproliferative properties in human melanoma cells and in this context may contribute to terminal cell differentiation. The mda-7 gene may also function as a negative regulator of melanoma progression.

Two isoforms of Drosophila dynamin in wild-type and shibire(ts) neural tissue: different subcellular localization and association mechanisms

The temperature-sensitive mutations of the shibire (shi) gene in Drosophila cause endocytic arrest, resulting in neurotransmission block and paralysis at high temperatures. However, underlying mechanism for the defects is not yet known. We examined the subcellular distribution of dynamin, a product of the shi gene, by immunoblotting and immunocytochemical assays. Two isoforms of dynamin with apparent M(r) of 92 kD and 94 kD have been detected in wild-type and shi(n) adult neural tissue. The two isoforms were reproducibly associated with different subcellular fractions of head homogenates. The 94kD isoform is fractionated in the low speed (2.000 x g) pellet containing plasma membrane fragments, and the 92kD isoform in the high speed (130,000 x g) pellet. In this procedure, very little dynamin remained in the high speed supernatant fraction. The 94 kD isoform represents the majority (65-75%) of total dynamin and appears to be a peripheral membrane protein. It can be extracted from the low speed membrane pellet by high salt, Na2CO3 (pH 11) or Triton X-100 treatments. Extracted 94kD dynamin from both wild-type and mutant homogenates is able to reassociate with artificial phospholipid vesicles at both permissive and restrictive temperatures. Binding of the 94 kD dynamin to liposomes appears to be pH-dependent, varying most significantly within the physiological pH range, which may be functionally important. The 92 kD isoform cannot be released by high salt or Na2CO3 treatments and only a small fraction is released by Triton X-100, suggesting a different mechanism of association with cell structures. The distribution of the two isoforms is not altered by the presence of stabilized microtubules in homogenates. No apparent degradation or subcellular redistribution of mutant dynamin was detected in two shi(n) alleles after heat shock or block of the dynamin GTPase activity, suggesting that intracellular redistribution or degradation of mutant dynamin are not involved in the endocytosis arrest in these mutants. These observations resemble the effect of endocytosis arrest by GTP-gamma-S in rat brain synaptosomes (Takei et al., 1995), in which dynamin is trapped at the neck of invaginated pits but is absent in the clathrin-coated distal end undergoing internalization. Our finding that endocytosis arrest by shi(n) mutations and GTP-gamma-S do not lead to cumulation of dynamin in the low speed pellet fraction further suggests that the 94 kD isoform remains associated with the plasma membrane during coated vesicle pinch-off and that the two isoforms do not appear to correspond to different functional states of dynamin but are likely to be involved in separate cellular compartments within the membrane cycling pathway (e.g., the plasma membrane, endosomes, and endoplasmic reticulum).

SCH 51344 inhibits ras transformation by a novel mechanism

A pyrazolo-quinoline compound, 6-methoxy-4-[2-[(2-hydroxyethoxyl)-ethyl]amino]-3-methyl-1M-pyrazo lo [3,4-b]quinoline (SCH 51344), was identified based on its ability to derepress human smooth muscle alpha-actin promoter activity in ras-transformed cells. In this study, we show that SCH 51344 reverts several key aspects of ras transformation, such as morphological changes, actin filament organization, and anchorage-independent growth, and also inhibits Val-12 Ras-induced maturation of Xenopus oocytes. SCH 51344 is also a potent inhibitor of the anchorage-independent growth of human tumor lines known to contain multiple genetic alterations in addition to activated ras genes. We have sought to determine whether SCH 51344 disrupts the signaling pathway that activates mitogen-activated protein (MAP) kinase or extracellular signal-regulated kinase (ERK) in normal and ras-transformed fibroblast cells. NIH 3T3 cells transformed by different oncogenes, which have products that participate at different steps of the Ras signaling pathway, were tested in a soft-agar colony formation assay to determine which step of the pathway is inhibited by SCH 51344. Our results indicate that SCH 51344 inhibits the ability of v-abl, v-mos, H-ras, v-raf, and mutant active MAP kinase kinase-transformed NIH 3T3 cells to grow in soft agar. Only v-fos-transformed cells were found to be resistant to the treatment of SCH 51344. SCH 51344 treatment had very little effect, if any, on the activation of MAP kinase kinase, MAP kinase, and p90RSK activity in response to growth factor stimulation. Treatment of ras-transformed cells with SCH 51344 led to stimulation of serum response factor DNA binding activity and activation of serum response element-dependent gene transcription, accounting for its ability to activate alpha-actin promoter activity in ras-transformed cells. Our results indicate that SCH 51344 inhibits ras transformation by a novel mechanism and acts at a point either downstream or parallel to extracellular signal-regulated kinase-dependent Ras signaling pathway.

Plasminogen activator inhibitor-1 and peritoneal transport in diabetic and non-diabetic peritoneal dialysis patients

Plasminogen activator inhibitor-1 (PAI-1) is an important regulator of plasminogen activators and has been shown to be involved in the accumulation of extracellular matrix (ECM) in various tissues. Since peritoneal interstitium is one of the main resistance sites of peritoneal transport, the level of PAI-1 in the peritoneum may have a significant effect on water and solute transport during peritoneal dialysis (PD) via its effect of peritoneal ECM. Therefore, we studied the associations between plasma or dialysate PAI-1 levels and the peritoneal transport during standard peritoneal equilibration test (PET) in 8 diabetic and 8 non-diabetic stable PD patients who were matched for their demographical data. There were no differences in plasma PAI-1 levels and PET variables between these two groups of patients. In each group, there was an increase in dialysate PAI-1 level with dwell time as a result of the diffusion of plasma PAI-1 into peritoneal cavity and the local production and release of PAI-1 in peritoneal tissue. However, the extent of this increase was less in the former. In non-diabetic patients, the change in dialysate PAI-1 amount was a significant positive predictor for the diffusive transports of urea and transport. These results are consistent with the hypothesis that peritoneal PAI-1 has a significant effect on peritoneal transport during PD. Further studies including more patients are needed to confirm our observations, and studies providing more direct evidence are needed to test this hypothesis.

Application of the polymerase chain reaction to monitor Mycobacterium tuberculosis DNA in the CSF of patients with tuberculous meningitis after antibiotic treatment

The polymerase chain reaction (PCR) was used to detect Mycobacterium tuberculosis DNA in 29 CSF specimens from seven patients with tuberculous meningitis after the start of antituberculous chemotherapy. Ten of the 13 CSF specimens taken from these patients with an initial treatment of three weeks were positive for the PCR study. By contrast, only one of the other 16 CSF specimens taken from patients treated for more than three weeks was positive. This study shows that M tuberculosis DNA can exist in the CSF of a patient with tuberculous meningitis for three weeks after treatment and that PCR can still be a sensitive method to detect M tuberculosis DNA in the CSF after the start of treatment in patients with tuberculous meningitis.

Alignment of caldesmon on the actin-tropomyosin filaments

We have reported previously that each smooth-muscle caldesmon binds predominantly to a region within residues 142-227 of tropomyosin, but a weaker binding site also exists at the N-terminal region of tropomyosin [Watson, Kuhn, Novy, Lin and Mak (1990) J. Biol. Chem. 265, 18860-18866]. In view of recent evidence for the presence of tropomyosin-binding sites at both the N- and C-terminal domains of caldesmon, we have studied the binding of the N- and C-terminal fragments of human fibroblast caldesmon expressed in Escherichia coli to tropomyosin and its CNBr fragments. The N-terminal fragment, CaD40 (residues 1-152), binds tropomyosin, but the interaction is mostly abolished in the presence of actin. CaD40 binds strongly to Cn1B(142-281) of tropomyosin, but weakly to Cn1A(11-127). The C-terminal fragment, CaD39, which corresponds to residues 443-736 of gizzard caldesmon, binds tropomyosin, and the interaction is enhanced by actin. CaD39 binds to both Cn1A(11-127) and Cn1B(142-281) of tropomyosin. Our results suggest that the N-terminal domain of caldesmon interacts with the C-terminal half of one tropomyosin molecule, whereas the C-terminal domain binds to both N- and C-terminal regions of the adjacent tropomyosin molecule along the actin filament. In addition, the binding of the N-terminal domain of caldesmon to the actin-tropomyosin filament is weak, which may allow this domain to project off the thin filament to interact with myosin.

A young adult with tuberculous meningitis diagnosed by polymerase chain reaction on serial CSF samples: a case report

A polymerase chain reaction (PCR) assay was used to diagnose a young adult with tuberculous meningitis who presented with unusual clinical symptoms of an acute illness. He had repeated cerebrospinal fluid (CSF) samples taken, and the PCR assay for detecting mycobacterial deoxyribonucleic acid was negative for the first two CSF specimens, but was positive in the third. He was then treated with antituberculous drugs and had complete restoration three months later. A follow-up PCR of the CSF was still positive after one month of therapy using antituberculous drugs, but converted to a negative result one month later. It is concluded that it is valuable to repeatedly sample CSF specimens for PCR study in patients with clinically suspected tuberculous meningitis.

Correlations between plasminogen activator inhibitor-1 and peritoneal transport in pediatric CCPD patients

OBJECTIVE

Plasminogen activator inhibitor-1 (PAI-1) is an important regulator of plasminogen activators and has been shown to be involved in the accumulation of extracellular matrix (ECM) in various tissues. Since peritoneal ECM is a resistance site for peritoneal transport, the production and release of PAI-1 in the peritoneum may affect the peritoneal transport of water and small solutes.

DESIGN

The linear correlations between the dialysate PAI-1 levels and the variables of peritoneal transport during peritoneal equilibration tests (PET) were examined.

SETTING

A tertiary university hospital.

PATIENTS

Six stable pediatric patients (age 10.8 +/- 4 years) undergoing continuous cycler-assisted peritoneal dialysis were included.

INTERVENTIONS

None.

RESULTS

All data are mean +/- SD. There was a positive correlation between the infused volume and the net ultrafiltration (UF, 198 +/- 127 mL, r = 0.82, p < 0.05). The dialysate PAI-1 levels increased during the dwell time (2.44 +/- 2.23 ng/mL or 2.46 +/- 1.72 micrograms at 4 hours vs 0.04 +/- 0.1 ng/mL or 0.04 +/- 0.09 micrograms at 0 hour, p < 0.05). The saturation indices (dialysate/plasma ratio) of PAI-1 and albumin at 4 hours were 1.05 +/- 1.21 and 0.028 +/- 0.004, respectively. The changes from 0 hour dwell to 4 hour dwell in the dialysate PAI-1 concentration (PAI4-0, 2.4 +/- 2.2 ng/mL) or amount corrected to body surface area (APAI4-0/BSA, 2.61 +/- 2.11 micrograms/m2) negatively correlated with UF or UF/body surface area and positively correlated with the number of episodes of peritonitis. There was no correlation between PAI4-0,APAI4-0/BSA, or plasma PAI-1 concentration and the mass transfer coefficient and clearance of either urea or creatinine.

CONCLUSIONS

The elevated PAI-1 level during the PET was likely from the local production and release of PAI-1. It had an inverse relationship with the amount of ultrafiltration. Repeated inflammation of the peritoneum was associated with an increased production and release of PAI-1 into the peritoneum.

An in vitro assay for Saccharomyces telomerase requires EST1

Telomerase activity was demonstrated in cell-free extracts from S. cerevisiae through the use of a PCR-based assay. As expected, this activity was eliminated by RNase or phenol treatment of the extract and was dependent on dGTP and dTTP. Telomerase was not detected in extracts prepared from cells grown for approximately 30 or more cell divisions in the absence of the EST1 product, Est1p. TLC1 RNA, which determines the sequence of telomeric DNA in vivo, was present in normal amounts in est1 delta cells. Moreover, TLC1 RNA specifically precipitated with epitope-tagged Est1p. These data indicate that Est1p is either a subunit of yeast telomerase or an accessory protein associated with telomerase that is essential in vitro for its activity.

Insulin-like growth factor-1 enhances epidermal growth factor receptor activation and renal tubular cell regeneration in postischemic acute renal failure

Growth factors such as insulin-like growth factor-1 (IGF-1), epidermal growth factor (EGF), and hepatocyte growth factor have been shown to accelerate the recovery from postischemic acute renal failure (ARF) with a concomitant increase in DNA synthesis. Interactions between growth factors have been demonstrated in a number of in vitro studies. This study examined the effect of exogenous IGF-1 on the DNA synthesis and EGF receptor (EGF-R) activation in postischemic rat kidneys. Thirty minutes after the relief of 30-minute total occlusion of the left renal artery in anesthetized 225 to 300 gm Sprague-Dawley rats, either IGF-1 (75 micrograms/kg) or normal saline solution (NS, 0.2 ml) was given by intravenous bolus, followed by twice daily subcutaneous injections of IGF-1 (50 micrograms/kg) or 0.2 ml NS for 4 days, respectively, in IGF-1-Tx) and NS treated (NS-Tx) groups (n = 8 each). On the day after the completion of treatment, inulin clearance (ml/kg/min) of the postischemic kidneys in the IGF-1-Tx group was significantly higher (p < 0.01) than inulin clearance of kidneys in the NS-Tx group. This was associated with improved kidney morphology. IGF-1 treatment also enhanced the labeling index of 5-bromo-2'-deoxyuridine (percent of stained tubule cells), a marker for active DNA synthesis, in the outer medulla of postischemic kidneys at 1 day and 2 days after the injury. EGF-R tyrosine phosphorylation (which reflects receptor activation) increased in postischemic kidneys in both NS-Tx (n = 5) and IGF-1-Tx (n = 3) groups 1 day after the injury as compared with nonischemic contralateral kidneys. In the IGF-1-Tx group there was also increased iodine 125-labeled EGF binding and EGF-R protein. Our results demonstrate a beneficial effect of IGF-1 on postischemic ARF. Furthermore, they suggest that EGF-R activation is involved in tubular regeneration and that IGF-1 may enhance EGF-R activation by increasing EGF-R expression.

Rapid optimization of electroporation conditions for plant cells, protoplasts, and pollen

The optimization of electroporation conditions for maximal uptake of DNA during direct gene transfer experiments is critical to achieve high levels of gene expression in transformed plant cells. Two stains, trypan blue and fluorescein diacetate, have been applied to optimize electroporation conditions for three plant cell types, using different square wave and exponential wave electroporation devices. The different cell types included protoplasts from tobacco, a stable mixotrophic suspension cell culture from soybean with intact cell walls, and germinating pollen from alfalfa and tobacco. Successful electroporation of each of these cell types was obtained, even in the presence of an intact cell wall when conditions were optimized for the electroporation pulse. The optimal field strength for each of these cells differs, protoplasts having the lowest optimal pulse field strength, followed by suspension cells and finally germinating pollen requiring the strongest electroporation pulse. A rapid procedure is described for optimizing electroporation parameters using different types of cells from different plant sources.

Vertebral artery dissection complicated by cervical manipulation: a case report

A 32-year-old healthy man developed vomiting, blurred vision, and consciousness disturbance following cervical manipulation. Physical examination showed stuporous consciousness and spontaneous horizontal nystagmus. Computed tomography (CT) and magnetic resonance (MR) imaging of the brain revealed infarction in the territory of the basilar artery. Studies of MR angiography and vertebral angiography disclosed dissection of the right vertebral artery at the atlantoaxial segment. Antiedematous drugs were prescribed and the patient gradually improved. Neurologic examination six months later demonstrated mild cerebellar ataxia. Physicians and patients should be aware that vertebro-basilar dissection may follow cervical manipulation, and, more importantly, should attempt to prevent progressive infarction.

Forced expression of chimeric human fibroblast tropomyosin mutants affects cytokinesis

Human fibroblasts generate at least eight tropomyosin (TM) isoforms (hTM1, hTM2, hTM3, hTM4, hTM5, hTM5a, hTM5b, and hTMsm alpha) from four distinct genes, and we have previously demonstrated that bacterially produced chimera hTM5/3 exhibits an unusually high affinity for actin filaments and a loss of the salt dependence typical for TM-actin binding (Novy, R.E., J. R. Sellers, L.-F. Liu, and J.J.-C. Lin, 1993. Cell Motil. & Cytoskeleton. 26: 248-261). To examine the functional consequences of expressing this mutant TM isoform in vivo, we have transfected CHO cells with the full-length cDNA for hTM5/3 and compared them to cells transfected with hTM3 and hTM5. Immunofluorescence microscopy reveals that stably transfected CHO cells incorporate force-expressed hTM3 and hTM5 into stress fibers with no significant effect on general cell morphology, microfilament organization or cytokinesis. In stable lines expressing hTM5/3, however, cell division is slow and sometimes incomplete. The doubling time and the incidence of multinucleate cells in the stable hTM5/3 lines roughly parallel expression levels. A closely related chimeric isoform hTM5/2, which differs only in the internal, alternatively spliced exon also produces defects in cytokinesis, suggesting that normal TM function may involve coordination between the amino and carboxy terminal regions. This coordination may be prevented in the chimeric mutants. As bacterially produced hTM5/3 and hTM5/2 can displace hTM3 and hTM5 from actin filaments in vitro, it is likely that CHO-expressed hTM5/3 and hTM5/2 can displace endogenous TMs to act dominantly in vivo. These results support a role for nonmuscle TM isoforms in the fine tuning of microfilament organization during cytokinesis. Additionally, we find that overexpression of TM does not stabilize endogenous microfilaments, rather, the hTM-expressing cells are actually more sensitive to cytochalasin B. This suggests that regulation of microfilament integrity in vivo requires stabilizing factors other than, or in addition to, TM.

Expression of kappa opioid receptors in human and monkey lymphocytes

mRNA encoding the kappa opioid receptor gene sequence was identified and isolated from various human lymphocytic cells: CEM x174 (a hybrid of T and B origin) cells, Jurkat-T4 cells, human peripheral blood mononuclear cells (PBMC) and purified CD4+ cells. Analyzing the cDNA sequences of RNA transcripts spanning the putative second extracellular loop, which has reported dynorphin specificity, and the seventh transmembrane domain revealed a 100% and 95% homology in amino acid sequence to corresponding kappa opioid receptor sequences in human placenta and rat brain, respectively. Expression of a similar kappa opioid receptor sequence could be detected in normal monkey PBMC but not in monkey PBMC in which the CD4+/CD8+ cell ratio (or CD4+ cell number) was significantly reduced due to prolonged SIV infection. These findings suggest that human and monkey lymphocytes constitutively express kappa opioid receptor mRNA.

Thermal adaptation of cytoplasmic malate dehydrogenases of eastern Pacific barracuda (Sphyraena spp): the role of differential isoenzyme expression

Kinetic properties, electrophoretic patterns and thermal stabilities of cytoplasmic malate dehydrogenases (cMDHs) were compared in Eastern Pacific barracuda (Sphyraena spp) from different latitudes. All tissues of the tropical species S. ensis contained only a single, thermostable form of cMDH. Subtropical (S. lucasana) as well as north (S. argentea) and south (S. idiastes) temperate barracuda contained both thermostable and thermolabile cMDHs, the pattern characteristic of most teleosts. Kinetic studies using unfractioned cMDHs showed that the apparent Michaelis&shy;Menten constant (Km) of cofactor (NADH) increased with temperature, but at the physiological temperatures of the four species, Km of NADH was conserved within a narrow range (20&shy;23 &micro;mol l-1). Thermostable and thermolabile cMDHs were chromatographically separated and compared. Thermolabile cMDHs had higher Km values for NADH at all measurement temperatures than did thermostable cMDHs. Thermolabile cMDHs isolated from congeneric barracuda exhibited similar kinetic properties (Km versus temperature, optimal pH, optimal substrate and cofactor concentrations). Thermostable cMDHs, likewise, were similar among the barracuda. Conservation of Km in the differently thermally adapted barracudas is, therefore, apparently due to adjustments in the ratio of expression of the thermostable and thermolabile isoforms, rather than to temperature-adaptive differences among orthologous homologues, as is commonly found for enzymes encoded by a single gene locus. The effects of temperature on the Km of NADH for isolated thermostable and thermolabile cMDHs of a eurythermal goby, Gillichthys mirabilis, however, were consistent with adaptive change in orthologous homologues of cMDH. The selective basis for the absence of thermolabile cMDH in warm-adapted ectotherms, mammals and birds is discussed.

Rapid diagnosis of tuberculous meningitis by polymerase chain reaction assay of cerebrospinal fluid

A polymerase chain reaction (PCR) method for the rapid diagnosis of tuberculous meningitis (TBM) was used to study prospectively 47 cerebrospinal fluid (CSF) samples from 45 patients. Twenty CSF samples were from patients with clinically suspected TBM and another 27 samples came from patients without clinically suspected TBM. Mycobacterial DNA was detected in 15 CSF samples (14 from patients with clinically suspected TBM and 1 from a patient not suspected of having TBM). Of the PCR-positive samples, 4 were also positive for mycobacterial culture. However, 32 PCR-negative samples were all culture-negative. All samples were negative for the acid-fast bacillus by direct smear. The single PCR-positive patient in the clinically unsuspected TBM group was initially diagnosed as suffering from aseptic meningitis on the basis of his clinical features. The mycobacterial culture of his CSF specimen was also positive and a revised diagnosis of an aseptic type of TBM was made. The estimations of specificity and sensitivity in this study were 100% and 70% respectively. The results showed that using a PCR to detect mycobacterial DNA in CSF for the early diagnosis of TBM is not only a rapid but also an accurate method.

Hemiballism-hemichorea: clinical study in 23 Chinese patients

BACKGROUND

Hemiballism-hemichorea, a well documented movement disorder, is not uncommon in the clinic. However, systematic analysis of the condition in ethnic Chinese on clinical grounds, is still inexplicably lacking.

METHODS

This study focused on 23 Chinese patients with hemiballism-hemichorea in Taiwan. The general data, clinical pictures, blood biochemistries, past histories of systemic disease, neuroradiological imaging, methods of treatment, and prognoses of these patients were analyzed retrospectively.

RESULTS

The study revealed that ischemic stroke (44%) is the leading cause of this movement disorder, and the metabolic disorder (22%) is also one of the common etiologies of dyskinesia in Chinese patients. In addition to those patients whose condition was caused by non-ketotic hyperglycemia, blood sugar had also obviously increased in patients where the cause was infarction. Pathological lesions contributed to hyperkinesia were found not only in the contralateral basal ganglion but also in the thalamus and subcortical areas. The characteristics of those patients where the cause was infarction and non-ketotic hyperglycemia were: age at onset greater than 60 years, and predominantly in women. Etiologies contributing to this movement disorder in younger patients differ from those in the older. Prognosis of the movement disorder in this study was favorable.

CONCLUSIONS

Hemiballism-hemichorea is predisposed to occur in older Chinese women, and metabolic disorder is an important etiology of the movement disorder. When the dyskinesia is encountered in the clinic, the metabolic disorders must be first ruled out as the problem may be rapidly resolved by achieving metabolic control.