Relationships between symptoms of schizophrenia and substance abuse

Previous work posits that severity of substance abuse and severity of schizophrenic symptoms should be linked by either or both of two mechanisms: self-regulation of symptoms and drug-induced exacerbation of symptoms. Research on these relationships has yielded mixed results. We examined the interrelationships of schizophrenic symptoms and substance abuse in 172 patients with co-occurring disorders. Relationships were weak or nonexistent, without any consistent pattern. Our findings do not support the view that substances are used to self-regulate symptoms. In addition, our results suggest that substance abuse may lead to higher rates of institutionalization through mechanisms other than by exacerbating symptoms.

[Evaluation of ligature-induced periodontitis in minipig]

We evaluated the progressing period of ligature induced periodontitis in chinese minipig. Plaque index (PLI), bleeding index (BI), probing pocket depth (PD) and clinical attachment level (CAL) were measured in 3 minipigs. On weeks 4 and 8, there was a significant increase of the mean values of PD and CAL. After this active phase, there was no further destruction up to 20 weeks. Following ligature removed probing depths decreased in 3 weeks, but they did not restore to the baseline. It suggests that using ligature induced periodontitis model to evaluate the treatment therapy and medicine effect have to consider the self-healing of lesions, when a treatment trail is carried out in a model.

Protein kinase C modulates flow-initiated contraction

The objective of this study was to determine whether protein kinase C (PKC) activation is involved, and what its role might be, in flow-induced contraction. Contractions induced by flow (40 microliters/min), K+ (25 mM) and histamine (300 nM) in segments of the rabbit fatal vein were compared under isometric conditions. The PKC activator 12-O-tetradecanoylphorbol-13-acetate (50 nM) significantly enhanced flow-induced and K(+)-induced, but not histamine-induced, contractions. Down-regulation of PKC by preincubation with phorbol 1,13-dibutyrate (10 nM for 24 hr) markedly inhibited flow contraction. Although histamine-induced contraction was also affected, the response to K+ remained unchanged. The potentiation of flow-induced contraction by 12-O-tetradecanoylphorbol-13-acetate was prevented by the voltage-gated Ca+2 channel antagonist diltiazem (1 microM). When the PKC activator 12-O-tetradecanoylphorbol-13-acetate (50 nM) was added in a Ca(+2)-free medium containing manganese (1 mM), flow-induced and 25 mM K(+)-induced contractions were enhanced and unaltered, respectively, but histamine-induced contraction was reduced. It is argued that of three types of contractions studied, PKC predominantly modulates flow-induced contraction. PKC can influence this contraction through increases in both Ca++ entry and Ca++ sensitivity.

Insulin resistance caused by hepatic cholinergic interruption and reversed by acetylcholine administration

The role of hepatic parasympathetic nerves in insulin effectiveness was evaluated in fed anesthetized rats. Insulin sensitivity was assessed using a modified euglycemic clamp to quantitate the amount of glucose required to maintain euglycemia over 60 min after administration of insulin (50 mU/kg). With normal innervation, intraportal infusions of acetylcholine (ACh, 2.5 micrograms.kg-1.min-1) did not alter insulin sensitivity, but intraportal venous atropine (3 mg/kg) reduced insulin sensitivity (49.4 +/- 5.8%, P < 0.001, n = 7). Liver denervation resulted in reduction of insulin responsiveness by 70.8 +/- 5.8% (P < 0.001, n = 8), which was fully (96.8 +/- 12.5%) reversed by ACh. ACh into the portal vein reversed insulin resistance produced by denervation, but intravenous ACh was without effect, thus showing that the liver was the site of ACh action. Regression analysis suggests that some component of insulin response is not dependent on hepatic cholinergic nerve effects but that virtually all of the variability in response to insulin in normal fed rats tested under these conditions could be accounted for by variability in the hepatic parasympathetic-dependent insulin sensitivity. These data suggest a major role for hepatic parasympathetic nerves in regulation of whole body clearance of glucose in response to insulin.

[Effect of intrahippocampal microinjection of enkephalin on cellular immune function and brain IL-1 alpha gene expression in rat]

The effect of intrahippocampal microinjection of enkephalin on cellular immune function and hippocampal IL-1 alpha gene expression was studied in rats. The results showed that: (1) The proliferation activity of splenic lymphocytes stimulated by Con A was significantly increased with microinjection of Leu-enkephalin 1 microliter (18 mmol/L) or Met-enkephalin 1 microliter (18 mmol/L) into bilateral hippocampus, but was inhibited by Lipopolysaccharide 1 microliter (50 ng/microliter). The proliferative response of splenic lymphocytes to Leu-enkephalin still persisted after bilateral adrenalectomy. Low doses of Leu- or Met-enkephalin (10(-10), 10(-11) mol/L) were also capable of causing proliferative activity of the Con A- stimulated cultured splenic lymphocytes in vitro. (2) Using RT-PCR technique, IL-1 alpha gene expression was detected in hippocampus 90 min after bilateral intrahippocampal injection of LPS. The LPS-induced IL-1 alpha gene expression in hippocampus could no longer be detected 30 min after microinjection of Met- or Leu-enkephalin into hippocampus. The above results suggested that intrahippocampal enkephalin might play an important role in neuro-immunomodulation by enhancing the inhibition of IL-1 alpha gene expression in hippocampal formation.

IA-2, a transmembrane protein tyrosine phosphatase, is expressed in human lung cancer cell lines with neuroendocrine phenotype

IA-2 is a transmembrane protein tyrosine phosphatase isolated recently from a human insulinoma subtraction library. Its expression in normal human tissues is restricted primarily to the pancreatic islets and brain. In this report, we describe the expression of IA-2 mRNA in a panel consisting of 20 lung tumor cell lines with neuroendocrine and non-neuroendocrine phenotype and 17 non-lung tumor cell lines. IA-2 mRNA was detected in 8 of 11 neuroendocrine small cell lung carcinomas, 4 of 4 non-small cell lung carcinomas with neuroendocrine phenotype, and 11 of 12 non-lung neuroendocrine tumor cell lines. In contrast, IA-2 mRNA was not detected in five non-neuroendocrine lung carcinomas, nor in a panel of other non-neuroendocrine tumor cell lines. The expression pattern of IA-2 mRNA suggests that IA-2 may represent a new marker for neuroendocrine differentiation In human lung cancer cells and perhaps other neuroendocrine tumors.

Mitogenic signaling from the egf receptor is attenuated by a phospholipase C-gamma/protein kinase C feedback mechanism

We recently demonstrated that epidermal growth factor receptor (EGFR)-mediated signaling of cell motility and mitogenesis diverge at the immediate post-receptor level. How these two mutually exclusive cell responses cross-communicate is not known. We investigated a possible role for a phospholipase C (PLC)-dependent feedback mechanism that attenuates EGF-induced mitogenesis. Inhibition of PLC gamma activation by U73122 (1 microM) augmented the EGF-induced [3H]thymidine incorporation by 23-55% in two transduced NR6 fibroblast lines expressing motility-responsive EGFR; increased cell division and mitosis was observed in parallel. The time dependence of this increase revealed that it was due to an increase in maximal incorporation and not a foreshortened cell cycle. Motility-responsive cell lines expressing a dominant-negative PLC gamma fragment (PLCz) also demonstrated augmented mitogenic responses by 25-68% when compared with control cells. PLCz- or U73122-augmented mitogenesis was not observed in three non-PLC gamma activating, nonmotility-responsive EGFR-expressing cell lines. Protein kinase C (PKC), which may be activated by PLC-generated second messengers, has been proposed as mediating feedback attenuation due to its capacity to phosphorylate EGFR and inhibit the receptor's tyrosine kinase activity. Inhibition of PKC by Calphostin C (0.05 microM) resulted in a 57% augmentation in the fold of EGF-induced thymidine incorporation. To further establish PKC's role in this feedback attenuation mechanism, an EGFR point mutation, in which the PKC target threonine654 was replaced by alanine, was expressed. Cells expressing these PKC-resistant EGFR constructs demonstrated EGF-induced motility comparable to cells expressing the threonine-containing EGFR. However, when these cells were treated with U73122 or Calphostin C, the mitogenic responses are not enhanced. These findings suggest a model in which PKC activation subsequent to triggering of motility-associated PLC gamma activity attenuates the EGFR mitogenic response.

Signaling pathways for antigen receptor-mediated induction of transcription factor CREB in B lymphocytes

We previously reported that cross-linking surface immunoglobulin (sIg) leads to induction of the transcription factor CREB in B lymphocytes through phosphorylation at Ser133, despite the lack of an increase in cAMP. Further, cAMP-raising agents fail to induce CREB Ser133 phosphorylation and CRE-dependent gene expression in these cells, which differs sharply from the situation in PC12 rat pheochromocytoma cells where CREB responds to elevation of cAMP through the activity of protein kinase A. In this study, we characterized the signal transduction pathways leading from sIg engagement to CREB activation. By using specific inhibitors for protein kinase C (PKC), Ca2+/calmodulin-dependent protein kinase II (CaM kinase II), and protein kinase A (PKA), we found that anti-Ig-induced CREB Ser133 phosphorylation depends on PKC, but does not require activation of PKA or CaM kinase II. The differential responsiveness of CREB to forskolin in PC12 cells and BAL-17 B cells may relate to the more marked elevation of cAMP in the former as opposed to the latter; however, high concentrations of dbcAMP which should readily enter B cells and artificially increase cAMP levels still failed to induce CREB Ser133 phosphorylation, even in conjunction with a phosphodiesterase inhibitor. Taken together, the cAMP/PKA pathway does not appear to be as active a contributor to CREB phosphorylation in B lymphocytes as in PC12 cells, and does not appear to be involved in sIg-induced, PKC-dependent, CREB activation.

Liver-targeted antiviral nucleosides: enhanced antiviral activity of phosphatidyl-dideoxyguanosine versus dideoxyguanosine in woodchuck hepatitis virus infection in vivo

It would be desirable to develop antiviral agents that can be targeted to liver to enhance their antiviral effects and reduce nonhepatic toxicity. 2',3'-Dideoxyguanosine (ddG) has been found to be a potent and selective antihepatitis B agent both in vitro and in vivo. To evaluate ddG and its liver-targeted analog, we synthesized a series of phosphatidyl-ddGs and incubated them with 2.2.15 cells, which chronically produce hepatitis B virus. 1,2-Dipalmitoylphosphatidyl-dideoxyguanosine (DPP-ddG) inhibited the production of hepatitis B virus (HBV) DNA in the culture medium by 90% at 4.5 mumol/L versus 9.1 mumol/L for ddG, while the liposome vehicle itself had no effect. To compare the efficacy of free ddG with its lipid prodrug in vivo, we treated woodchucks that were experimentally infected with woodchuck hepatitis virus (WHV) for 4 weeks by intraperitoneal injection of 2.6 mumol/kg/d of free ddG or liposomes containing 2.6 mumol/kg/d of DPP-ddG. Liposomal DPP-ddG reduced serum WHV DNA by 23- to 46-fold at the end of the fourth week, while free ddG reduced serum WHV DNA by 2.2- to 10.4-fold. Treatment with small unilamellar liposomes containing DPP-ddG is substantially more effective than free ddG in reducing WHV-DNA levels in serum in WHV-infected woodchucks. The data suggest that the use of lipid prodrugs to target the liver may be useful in enhancing antiviral therapy of hepatitis.

Insulin resistance of skeletal muscle produced by hepatic parasympathetic interruption

The objective was to determine the site of insulin resistance produced by intraportal atropine or surgical hepatic denervation. A modified euglycemic clamp was used in fasted cats to test the acute effect of insulin (100 mU/kg) on arteriovenous glucose gradients across the hindlimbs (mainly reflecting skeletal muscle), the guts (all organs draining into the portal vein), and the liver. Responses to insulin were determined before and after hepatic denervation and after 3 mg/kg intraportal atropine. The interventions were done in random order. Responses after either intervention were similar and were not potentiated by the combined treatment. Regional insulin resistance was assessed by comparing the change in glucose gradients in response to insulin before and after treatments. Hepatic and gut responses to insulin were unaltered, but hindlimb responses were significantly impaired after denervation or atropine. We speculate that the hepatic parasympathetic nerves regulate release of a liver-generated factor that selectively controls insulin effectiveness in skeletal muscle. This mechanism may be involved with insulin resistance in non-insulin-dependent diabetes and chronic liver disease.

Insulin sensitivity tested with a modified euglycemic technique in cats and rats

A new insulin sensitivity test (IST) is described using a modified euglycemic clamp in cats and rats. The IST uses the amount of glucose required to be infused to maintain euglycemia over a 30-min period in rats and 60 min in cats following a bolus administration of insulin as the index of insulin sensitivity. Glucose levels are determined at short time intervals (2-5 min), and variable glucose infusion is used to hold glucose levels within a few percentage points of the basal pre-test glucose level. A new blood sampling procedure is described that allows each IST to be carried out using a total of only 0.5 mL of blood. The IST is sensitive and allows clear insulin dose effects to be demonstrated with 100 mU/kg requiring 355.0 +/- 14.3 mg/kg over 30 min and 50 mU/kg requiring 198.7 +/- 11.1 mg/kg. Five consecutive tests were reproducibly carried out (%CV = 3.0 +/- 0.5) over a 12-hr period in the cat with insulin, glucagon, and glucose levels remaining stable prior to each IST. Glucagon and norepinephrine plasma concentrations do not change significantly during the IST. The IST is sufficiently sensitive to allow demonstration of dose-response relationships for atropine-induced insulin resistance. The IST is thus sensitive, reproducible, and able to demonstrate acute insulin resistance in anesthetized cats and rats. The test is demonstrated in fed (rats) and fasted (cats) state.

Identification of a second transmembrane protein tyrosine phosphatase, IA-2beta, as an autoantigen in insulin-dependent diabetes mellitus: precursor of the 37-kDa tryptic fragment

A novel cDNA, IA-2beta, was isolated from a mouse neonatal brain library. The predicted protein sequence revealed an extracellular domain, a transmembrane region, and an intracellular domain. The intracellular domain is 376 amino acids long and 74% identical to the intracellular domain of IA-2, a major autoantigen in insulin-dependent diabetes mellitus (IDDM). A partial sequence of the extracellular domain of IA-2beta indicates that it differs substantially (only 26% identical) from that of IA-2. Both molecules are expressed in islets and brain tissue. Forty-six percent (23 of 50) of the IDDM sera but none of the sera from normal controls (0 of 50) immunoprecipitated the intracellular domain of IA-2beta. Competitive inhibition experiments showed that IDDM sera have autoantibodies that recognize both common and distinct determinants on IA-2 and IA-2beta. Many IDDM sera are known to immunoprecipitate 37-kDa and 40-kDa tryptic fragments from islet cells, but the identity of the precursor protein(s) has remained elusive. The current study shows that treatment of recombinant IA-2beta and IA-2 with trypsin yields a 37-kDa fragment and a 40-kDa fragment, respectively, and that these fragments can be immunoprecipitated with diabetic sera. Absorption of diabetic sera with unlabeled recombinant IA-2 or IA-2beta, prior to incubation with radiolabeled 37-kDa and 40-kDa tryptic fragments derived from insulinoma or glucagonoma cells, blocks the immunoprecipitation of both of these radiolabeled tryptic fragments. We conclude that IA-2beta and IA-2 are the precursors of the 37-kDa and 40-kDa islet cell autoantigens, respectively, and that both IA-2 and IA-2beta are major autoantigens in IDDM.

Characterization and chromosomal localization of a new protein disulfide isomerase, PDIp, highly expressed in human pancreas

Protein disulfide isomerase (PDI) catalyzes protein folding and thiol-disulfide interchange reactions. The enzyme is localized in the lumen of endoplasmic reticulum (ER) and is abundant in secretory cells of various tissues. In this study we describe the isolation and characterization from human pancreas of a new protein, PDIp, that is structurally and functionally related to PDIs. PDIp cDNA is 1,659 bp in length and predicts a protein with an open reading frame of 511 amino acids. PDIp amino acid sequence shows 46% identity and 66% similarity to that of human PDI. PDIp possesses two thioredoxin-like active sites (WCGHCQ and WCTHCK) and an endoplasmic reticulum retention signal sequence, KEEL, at the carboxyl terminus. Northern analysis of normal human tissues and various human tumor cell lines revealed PDIp mRNA (2.0 kb) expression only in the normal pancreas. Recombinant PDIp protein catalyzed reductive cleavage of insulin and renaturation of reduced RNaseA. Somatic cell genetics and fluorescence in situ hybridization localized the PDIp gene to the short arm of human chromosome 16. It is concluded that PDIp is a new member of the PDI family and is highly expressed in human pancreas.

Intracellular Ca2+ release in flow-induced contraction of venous smooth muscle

We designed the present study to determine whether Ca2+ release from intracellular stores contributes to flow-induced contraction. We carried out experiments on segments of rabbit facial vein under isometric conditions. Intraluminal flow by perfusion of physiological salt solution (10 to 80 microL/min) caused contraction in this vessel, which was significantly inhibited by (1) 30-minute pretreatment with 10 mumol/L ryanodine, the sarcoplasmic reticulum Ca2+ channel opener, and (2) 30-minute pretreatment with concomitant application of 20 mmol/L caffeine and 1 mumol/L cyclopiazonic acid in Ca(2+)-free medium to deplete the sarcoplasmic reticulum. In comparison, contraction initiated by 300 nmol/L histamine was significantly attenuated by the same interventions. K+ (25 mmol/L)-induced contraction was unaffected by ryanodine but was reduced after depletion of the sarcoplasmic reticulum. The phospholipase C inhibitor 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate (10 mumol/L) inhibited contractions induced by flow and histamine but not by K+. These findings indicate that Ca2+ release from intracellular stores, presumably via the phosphatidylinositol pathway, contributes to flow- and histamine- but not raised K(+)-induced contractions in this vessel.

[Cataract after silicone oil tamponade and its surgical treatment]

Twelve eyes of twelve cases of cataract after complicated retinal detachment surgery and silicone oil tamponade were treated in this report. Successful extracapsular cataract extraction (ECCE) was performed on 10 of the 12 cases, no oil escape occurred in any of the operation and in one eye an intraocular lens was implanted. Intraoperatively, loss of large amount of silicone oil occurred and it was removed completely in ECCE in 2 cases. After the follow-up periods of 3 approximately 30 months (mean, ten months), ten cases with the intact posterior capsule and silicone oil in place had a good view of the fundus, their retinae were attached and visual acuities were recovered above the best levels after retinal detachment surgery. Two cases with silicone oil removal suffered from retinal re-detachment. The main points of the surgery were discussed, and the effective method of prevention from silicone oil escape and maintenance of the transparency of the posterior capsule after ECCE were proposed.

In vitro invasiveness of DU-145 human prostate carcinoma cells is modulated by EGF receptor-mediated signals

Prostate carcinomas often present an autocrine stimulatory loop in which the transformed cells both express the EGF receptor (EGFR) and produce activating ligands (TGF alpha and EGF forms). Up-regulated EGFR signalling has been correlated with tumor progression in other human neoplasia; however, the cell behaviour which is promoted remains undefined. To determine whether an EGFR-induced response contributes to cell invasiveness, we transduced DU-145 human prostate carcinoma cells with either a full-length (WT) or a mitogenically-active but motility-deficient truncated (c'973) EGFR. The DU-145 Parental and two transgene sublines all produced EGFR and TGF alpha, but the transduced WT and c'973 EGFR underwent autocrine downregulation to a lesser degree, with more receptor remaining intact. DU-145 cells transduced with WT EGFR transmigrated a human amniotic basement membrane matrix (Amgel) to a greater extent than did Parental DU-145 cells (175 +/- 22%). Cells expressing the c'973 EGFR invaded through the Amgel only to about two thirds the extent of the Parental cells (62 +/- 23%). A monoclonal antibody which prevents ligand-induced activation of EGFR decreased the invasiveness of WT-expressing cells by half and Parental cells by a fifth, but had little effect on the invasiveness of c'973-expressing cells; with the result that in the presence of antibody, all three cell lines transmigrated the Amgel to the same extent. The different levels of invasiveness between the three sublines were independent of cell proliferation. These findings demonstrated that EGFR-mediated signals increase tumor cell invasiveness and suggested that domains in the carboxy-terminus are required to signal invasiveness. As an initial investigation into the mechanisms underlying the EGFR-mediated enhanced invasiveness, we determined whether these cells presented different collagenolytic activity, as the major constituents of Amgel are collagen types I and IV. All three sublines secreted easily detectable levels of gelatin-directed proteases and TIMP-1, with WT cells secreting equivalent or lower levels of proteases. The proteolytic balance in these cells did not correlate with invasiveness. These data suggest that the TGF alpha-EGFR autocrine loop promotes invasiveness and that this is accomplished by signalling cell properties other than differential secretion of collagenolytic activity.

Phosphatidyl-2',3'-dideoxy-3'-thiacytidine: synthesis and antiviral activity in hepatitis B-and HIV-1-infected cells

We recently found that phosphatidyl-2',3'-dideoxycytidine (phosphatidyl-ddC) had substantial anti-hepatitis B virus (HBV) activity in vitro compared to 2',3'-dideoxycytidine (ddC) (Hostetler et al. (1994) Antiviral Res. 24, 59-67). Upon administration of liposomal phosphatidyl-ddC to mice, a 40-fold higher drug area under curve was observed in the liver. To evaluate the possibility of using liver-targeted anti-HBV nucleosides to treat woodchuck hepatitis virus, we wanted to find the most potent and selective lipid conjugates. It has been shown that 2',3'-dideoxy-3'-thiacytidine as a racemic mixture of the cis-isomer (cis-(+/-)-BCH-189) has much greater activity against HBV viruses than ddC in vitro. Recently, it was shown that the (-)-beta-L-enantiomer (3TC) is more active and less toxic than the (+)-beta-D-form ((+)-BCH-189). To determine whether phospholipid conjugates of 3TC retain antiviral activity in 2.2.15 cells as demonstrated previously with ddC, we synthesized the 1,2-dipalmitoyl-sn-glycerol-3-phosphate conjugates of (+/-)-BCH-189 and 3TC and assessed their anti-HBV and anti-HIV activities, in vitro. Phosphatidyl-3TC and phosphatidyl-BCH-189 had antiviral activity comparable to the respective free drugs in 2.2.15 cells which chronically produce HBV. In HIV-1-infected human peripheral blood mononuclear cells and HT4-6C cells, phosphatidyl-3TC and phosphatidyl-(+/-)-BCH-189 exhibited significantly lower activity than the corresponding free nucleosides. In view of the documented ability of phosphatidyl-ddC to target drug to the liver, it seems reasonable to expect that phosphatidyl-3TC or phosphatidyl-(+/-)-BCH-189 could be employed to provide greatly enhanced hepatic antiviral activity in HBV infection in vivo.

Induction of insulin resistance by cholinergic blockade with atropine in the cat

1. Insulin sensitivity was quantified using a modified euglycaemic technique after hepatic cholinergic blockade with atropine and compared with that after surgical denervation. 2. Intraportal administration of atropine produced dose-dependent inhibition of insulin sensitivity in glucose metabolism. ED50 of atropine was 0.99 mg kg-1 (1 mg = 1.5 microM) with maximum inhibition of 40.3 +/- 11.6%. 3. Atropine (3 mg kg-1) reduced insulin sensitivity by a similar amount (33.6 +/- 3.4%) to that produced by hepatic surgical denervation (37.8 +/- 9.8%). Doses greater than 3 mg kg-1 failed to further alter the insulin resistance produced by surgical denervation or atropine (3 mg kg-1) administration, suggesting that activation of hepatic parasympathetic nerves is necessary to fully express the insulin effect. 4. Atropine reduced insulin sensitivity without changes in plasma concentrations of glucagon or insulin. The temporal response to insulin in this euglycaemic study was not changed after atropine administration or after surgical hepatic denervation. 5. It is suggested that hepatic parasympathetic nerves show a synergistic effect with insulin. Disease states that result in hepatic parasympathetic neuropathy would be expected to produce an insulin resistant liver. 6. The modified euglycaemic clamp method for assessing insulin responses was shown to be reproducible up to four times in the same animal and was sufficiently sensitive and quantitative to be able to generate a dose-response curve in each animal for atropine-induced insulin resistance.

Risedronate pretreatment does not hamper the anabolic effects of prostaglandin E2 in ovx rats

Pretreatment of an anti-resorptive agent on the anabolic effects of prostaglandin E2 (PGE2) was studied on the proximal tibia and tibial shaft of ovariectomy (ovx) rats. Two days after ovx, rats were treated with either risedronate (Ris, 5 micrograms/kg twice weekly) or vehicle (V) for 60 days and then switched to 3 or 6 mg/kg/d PGE2 for 21 or 90 days. Bone area of both proximal tibial metaphysis (PTM) and tibial shaft (TX) were measured. Pretreatment with Ris increased the bone mass in PTM but not in TX of ovx rats. In the PTM, PGE2 produced the same percentage of new bone mass in both V- and Ris-pretreated ovx rats. The amount of new bone was almost the same after 3 weeks and 12 weeks of PGE2 treatment. There was no difference in the anabolic effects of 3 and 6 mg PGE2/kg/d in V-pretreated rats; however, the effects in Ris-pretreated groups were greater with 6 mg PGE2/kg/d than with 3 mg PGE2/kg/d. In TX, only the 6mg PGE2/kg/d administration added new bone on endocortical surfaces of both V- or Ris-pretreatment rats which leads to thickening the minimal cortical width, decreasing the marrow cavity and increasing total bone area. Both doses of PGE2 created new trabecular bone in the marrow cavity of tibial shaft in both vehicle- and Ris-pretreated ovx rats. These results suggest that Ris-pretreatment did not hamper the anabolic effects of PGE2 on either PTM or TX in ovx rats.

Blocking Ca(2+)-dependent synaptic release delays motoneuron differentiation in the rat spinal cord

Development of motoneuron electrical properties and excitability was studied in spinal cord explants of rat embryos cultured for 1-3 weeks. The morphological organization of the spinal cord and synaptic inputs onto motoneurons were maintained in organ culture. The rate of differentiation of motoneuron resting potential and increase in membrane excitability was similar in vitro and in vivo, suggesting that these properties were regulated by cellular signals or extracellular differentiation-promoting factors that were preserved in culture. However, maturation of input resistance, action potential threshold and action potential maximum rate of rise was slower than in vivo. Culturing spinal cord explants with their dorsal root ganglia attached did not facilitate motoneuron differentiation. The role of newly formed synaptic pathways in regulating the changes in motoneuron electrical properties was studied in the presence of blockers of synaptic transmission. Motoneuron differentiation was delayed in spinal cords cultured in the presence of TTX, indicating that electrical activity influenced the time course of their development. However, blocking synaptic transmission with antagonists of glutamate, glycine, and GABAA receptors did not affect the rate of motoneuron differentiation, suggesting that maturation of motoneuron phenotype was independent of activation of these transmitter-gated channels. Incubating spinal cords in medium containing high-K+, which increased the frequency of spontaneous potentials, reversed the inhibitory effect of TTX. Similar to TTX action, motoneuron development was retarded when synaptic release was chronically blocked with either tetanus toxin or omega-conotoxin, a Ca2+ channel blocker. These findings suggested that electrical activity in spinal cord explants modulated motoneuron differentiation via Ca(2+)-dependent synaptic release of neurotransmitters or neurotrophic factors.

[Study on the lung targeting gelatin microspheres of streptomycin sulphate]

This paper is reported the technology of lung targeting gelatin microspheres of streptomycin sulphate (SMS). The microspheres were prepared with natural biodegradable gelatin as the load material and castor oil as the oil phase. The experimental conditions were optimized, the mean volume diameter obtained being 9.7 microns and the mean rate of encapsulation 15.69%. The content, shape and size of the microspheres showed no remarkable change after storage at 37 degrees C RH 75% for 3 months. Activation energy of heat decomposition E = 75.86kJ/mol. In vitro, the SMS release rate was found to accord with Higuchi equation with t1/2 = 8.6h. In vivo (rabbits) the gelatin microspheres were proved to be concentrated in the lung.

A diffusing sphere which delivers homogeneous laser light for use in photodynamic therapy

Photodynamic therapy (PDT) exploits the selective uptake of a photosensitizer in tumors and other hyperproliferative target tissues, as well as the ability to direct the treatment light beam to a specific region. Since the photodynamic effect depends on light dose, tissue optical properties and photosensitizer concentration, uniform delivery of light is crucial to attain optimal photodynamic effect. Many commonly used methods for delivering laser light during photodynamic therapy, such as a free fiber or microlens, require fiber and laser adjustments to obtain a highly uniform beam. In this study, we test the ability of a diffusing sphere to improve the uniformity of a light field coming from an argon laser coupled to a free fiber, in which no attempt has been made to optimize beam characteristics. Light fields from the free fiber, a microlens and the diffusing sphere are compared for uniformity via light intensity readings. An in vivo comparison between the sphere and the free fiber is also made in guinea pigs given Photofrin-II. The diffusing sphere decreases problems with shielding, allows quick and easy application of light by simply applying the device over the desired treatment area, and optimizes the desired photodynamic effect by producing ad highly uniform beam of light with no necessity to optimize light delivery by vibrating, looping or re-cleaving fibers.

Observation of changes in peripheral T-lymphocyte subsets by flow cytometry in patients with liver cancer treated with radioimmunotherapy

An analysis of lymphocyte subsets was performed in 24 patients with surgically verified unresectable hepatocellular carcinoma (HCC). In all cases, the hepatic artery was cannulated and ligated and a single dose of 131I-Hepama-1 monoclonal antibody (MAb) was infused through a hepatic artery catheter. Blood samples were obtained before infusion and 1 month post-infusion. The results indicated that the CD3+ T-cells (pan T-cells) were normal, whereas the CD4+ T-cells (T-helper/inducer cells) decreased and the CD8+ T-cells (T-suppressor/cytotoxic cells) increased significantly in comparison with the control group. So the CD4+:CD8+ ratio declined markedly. One month post-radioimmunotherapy (RIT), the T-cell subsets did not change, but CD4+, CD8+ and the CD4+:CD8+ ratio differed significantly between patients with and without sequential resection. The changes in the T-cell subsets were closely related to tumour capsule status and the human anti-murine antibody (HAMA) response, but no relationship was found between the tumour and administration of a moderate dose of radioimmunoconjugate. Therefore, determination of changes in the T-lymphocyte subsets and the CD4+:CD8+ ratio could be used as clinical and prognostic indicators in patients who have received RIT. Furthermore, RIT did not affect the distribution of T-cell subsets in patients with HCC.

Protein kinase C mediates activation of nuclear cAMP response element-binding protein (CREB) in B lymphocytes stimulated through surface Ig

The cAMP response element-binding protein (CREB) is generally considered to be responsive to elevation of cAMP through the activity of protein kinase A (PKA). Although it is well known that cAMP-raising agents can strongly influence B cell stimulation, the regulation of CREB has been little studied. Recently, cross-linking of surface Ig (sIg) was shown to result in trans-activation of a cAMP response element (CRE)-dependent promoter to which bound B cell CREB. In this study, we explored the mechanism underlying this unexpected linkage between sIg and CREB. We found that sIg cross-linking results in phosphorylation of CREB at Ser133. Although this phosphorylation step is mediated by PKA in pheochromocytoma cells, it depends on protein kinase C (PKC) in B lymphocytes. This conclusion is based on abrogation of sIg-induced CREB Ser133 phosphorylation by long-term phorbol-ester treatment to deplete PKC, and mimicking of sIg-induced CREB phosphorylation and CRE-dependent gene expression by short-term PKC agonism. Furthermore, CD40 ligand (CD40L) and LPS, two PKC-independent forms of B cell stimulation, failed to induce phosphorylation of CREB Ser133. These results suggest that CREB responds to specific surface-receptor signals in B cells and that this response is mediated by PKC. Interestingly, forskolin failed to induce phosphorylation of CREB Ser133 in B cells, although it did so in PC12 pheochromocytoma cells. Taken together with PKC mediation of CREB Ser133 phosphorylation in B cells, these results suggest that the dominant mode of CREB regulation is cell-type specific.

Protein kinase C mediates activation of nuclear cAMP response element-binding protein (CREB) in B lymphocytes stimulated through surface Ig

The cAMP response element-binding protein (CREB) is generally considered to be responsive to elevation of cAMP through the activity of protein kinase A (PKA). Although it is well known that cAMP-raising agents can strongly influence B cell stimulation, the regulation of CREB has been little studied. Recently, cross-linking of surface Ig (sIg) was shown to result in trans-activation of a cAMP response element (CRE)-dependent promoter to which bound B cell CREB. In this study, we explored the mechanism underlying this unexpected linkage between sIg and CREB. We found that sIg cross-linking results in phosphorylation of CREB at Ser133. Although this phosphorylation step is mediated by PKA in pheochromocytoma cells, it depends on protein kinase C (PKC) in B lymphocytes. This conclusion is based on abrogation of sIg-induced CREB Ser133 phosphorylation by long-term phorbol-ester treatment to deplete PKC, and mimicking of sIg-induced CREB phosphorylation and CRE-dependent gene expression by short-term PKC agonism. Furthermore, CD40 ligand (CD40L) and LPS, two PKC-independent forms of B cell stimulation, failed to induce phosphorylation of CREB Ser133. These results suggest that CREB responds to specific surface-receptor signals in B cells and that this response is mediated by PKC. Interestingly, forskolin failed to induce phosphorylation of CREB Ser133 in B cells, although it did so in PC12 pheochromocytoma cells. Taken together with PKC mediation of CREB Ser133 phosphorylation in B cells, these results suggest that the dominant mode of CREB regulation is cell-type specific.

Molecular basis of attenuation of neurovirulence of wild-type Japanese encephalitis virus strain SA14

To identify the molecular determinants for attenuation of wild-type Japanese encephalitis (JE) virus strain SA14, the RNA genome of wild-type strain SA14 and its attenuated vaccine virus SA14-2-8 were reverse transcribed, amplified by PCR and sequenced. Comparison of the nucleotide sequence of SA14-2-8 vaccine virus with virulent parent SA14 virus and with two other attenuated vaccine viruses derived from SA14 virus (SA14-14-2/PHK and SA14-14-2/PDK) revealed only seven amino acids in the virulent parent SA14 had been substituted in all three attenuated vaccines. Four were in the envelope (E) protein (E-138, E-176, E-315 and E-439), one in non-structural protein 2B (NS2B-63), one in NS3 (NS3-105), and one in NS4B (NS4B-106). The substitutions at E-315 and E-439 arose due to correction of the SA14/CDC sequence published previously by Nitayaphan et al. (Virology 177, 541-552, 1990). The mutations in NS2B and NS3 are in functional domains of the trypsin-like serine protease. Attenuation of SA14 virus may therefore, in part, be due to alterations in viral protease activity, which could affect replication of the virus.

Human anti-(murine Ig) antibody responses in patients with hepatocellular carcinoma receiving intrahepatic arterial 131I-labeled Hepama-1 mAb. Preliminary results and discussion

Human anti-(murine Ig) antibody (HAMA) responses were monitored in 32 patients with unresectable hepatocellular carcinoma (HCC) undergoing radioimmunotherapy using 131I-labeled anti-HCC monoclonal antibody (Hepama-1 mAb) intrahepatic arterial infusion. Dosages of Hepama-1 mAb ranged from 5 mg to 20 mg and the mAb was radiolabeled with 0.74-4.00 GBq (20-108 mCi) 131I (4-6 mCi/mg). T lymphocyte subsets were examined before and after radioimmunotherapy in 24 patients. In this series, 34.4% (11/32) of patients developed HAMA within 2-4 weeks after the infusion. All patients with a negative HAMA response (n = 14), had CD4+ T lymphocyte subsets (T helper/inducer) much lower than those of the HAMA-positive (n = 10) patients and the control group (n = 40) (P < 0.01) prior to infusion. The sequential resection and survival rates in the HAMA-negative group were also lower than that of the HAMA-positive group. Thus, the determination of T lymphocyte subsets might help to predict the HAMA response in HCC patients during radioimmunotherapy.

Effects of total coumarins of Fructus cnidii on skeleton of ovariectomized rats

Total coumarins of Fructus Cnidii (TCFC), 5 g.kg-1 by intragastric gavage, 6 d/wk, x 7 wk, was effective for prevention of bone loss in ovariectomized (OVX) rats. In comparison to aging control rats, the proximal tibia of placebo-treated OVX rats were characterized by an increase in eroded perimeter (+298%), label perimeter (+77%), osteoid perimeter (+47%), mineral apposition rate (+32%) and bone formation rate (+130%). These changes indicated a high bone turnover in OVX rats leading to a rapid bone loss (-44%) in proximal tibial metaphysis. In contrast, the TCFC-treated OVX rats showed an increase of cancellous bone area (+41%) compared with placebo-treated OVX rats and decrease in all the above indices of bone turnover to near aging control levels except that of the osteoid area (+88%) which was higher than that in aging control, but mineralization lag time did not show significant changes. The results suggested that the TCFC inhibited the high bone turnover and reversed the bone loss at early menopausal stage.

Epidermal growth factor receptor-mediated cell motility: phospholipase C activity is required, but mitogen-activated protein kinase activity is not sufficient for induced cell movement

We recently have demonstrated that EGF receptor (EGFR)-induced cell motility requires receptor kinase activity and autophosphorylation (P. Chen, K. Gupta, and A. Wells. 1994. J. Cell Biol. 124:547-555). This suggests that the immediate downstream effector molecule contains a src homology-2 domain. Phospholipase C gamma (PLC gamma) is among the candidate transducers of this signal because of its potential roles in modulating cytoskeletal dynamics. We utilized signaling-restricted EGFR mutants expressed in receptor devoid NR6 cells to determine if PLC activation is necessary for EGFR-mediated cell movement. Exposure to EGF (25 nM) augmented PLC activity in all five EGFR mutant cell lines which also responded by increased cell movement. Basal phosphoinositide turnover was not affected by EGF in the lines which do not present the enhanced motility response. The correlation between EGFR-mediated cell motility and PLC activity suggested, but did not prove, a causal link. A specific inhibitor of PLC, U73122 (1 microM) diminished both the EGF-induced motility and PLC responses, while its inactive analogue U73343 had no effect on these responses. Both the PLC and motility responses were decreased by expression of a dominant-negative PLC gamma-1 fragment in EGF-responsive infectant lines. Lastly, anti-sense oligonucleotides (20 microM) to PLC gamma-1 reduced both responses in NR6 cells expressing wild-type EGFR. These findings strongly support PLC gamma as the immediate post receptor effector in this motogenic pathway. We have demonstrated previously that EGFR-mediated cell motility and mitogenic signaling pathways are separable. The point of divergence is undefined. All kinase-active EGFR mutants induced the mitogenic response while only those which are autophosphorylated induced PLC activity. U73122 did not affect EGF-induced thymidine incorporation in these motility-responsive infectant cell lines. In addition, the dominant-negative PLC gamma-1 fragment did not diminish EGF-induced thymidine incorporation. All kinase active EGFR stimulated mitogen-activated protein (MAP) kinase activity, regardless of whether the receptors induced cell movement; this EGF-induced MAP kinase activity was not affected by U73122 at concentrations that depressed the motility response. Thus, the signaling pathways which lead to motility and cell proliferation diverge at the immediate post-receptor stage, and we suggest that this is accomplished by differential activation of effector molecules.

Zinc is an inhibitor of the stimulatory response of the sodium efflux to the microinjection of cyclic AMP and forskolin in single barnacle muscle fibers

The main aim of the experiments with which this paper deals was to test the hypothesis that Zn is an inhibitor of the stimulatory response of the ouabain-insensitive component of the Na efflux to the injection of cAMP, DcAMP (dibutyryl-cAMP) and FD (forskolin derivative) in barnacle muscle fibers. The results obtained were as follows: (1) External application of Zn caused a fall in the Na efflux in fibers poisoned with ouabain beforehand; (2) external application of Zn prior to the injection of cAMP, DcAMP and FD led to a marked reduction in the response of the Na efflux in fibers pre-treated with ouabain; (3) the response obtained by the injection of DcAMP and FD into ouabain-poisoned fibers pre-exposed to Zn was small but sustained; and (4) external application of Zn following peak stimulation by injecting DcAMP or FD led to reversal of this response. (Parallel experiments involving the injection of cAMP were not done, since the response following the onset of peak stimulation decays quite rapidly.) Taken together, these results support the hypothesis that Zn behaves as an inhibitor of the stimulatory response obtained by the injection of cAMP, DcAMP and FD.

The endothelium contributes to the contractile responses of the human umbilical artery to 5-hydroxytryptamine and endothelin-1 under low but not high PO2 conditions

To determine the influences of both PO2 and the presence of the endothelium on contractile responses of the human umbilical artery (HUA), the effects of a series of vasoconstrictors were compared in ring preparations with and without endothelium at low (2.5% O2, PO2 < 55 mmHg (1 mmHg = 133.3 Pa)) and high PO2 (95% O2, PO2 > 600 mmHg). The results demonstrate the following. (i) 5-Hydroxytryptamine (5-HT) and endothelin-1 (ET-1) contracted the HUA at either low or high PO2. At low PO2, removal of the endothelium significantly reduced receptor-mediated responses. (ii) The nitric oxide synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME, 100 microM) did not modulate 5-HT-initiated contractions at either level of PO2. (iii) alpha-Methyl-5-hydroxytryptamine (alpha-Me-5-HT) and 5-carboxamidotryptamine (5-CT), relatively selective 5-HT1C/5-HT2 and 5-HT1-like receptor agonists, respectively, elicited contractions in the HUA, and the responses were reduced at low PO2 but unaffected by removal of the endothelium. (iv) Responses of the HUA to high potassium (hK+) were unaffected by either changes in PO2 or removal of the endothelium. (v) The 5-HT2 receptor antagonist ketanserin at low concentration (10 nM) inhibited contractile responses to 5-HT in an apparently competitive manner. However, with 100 nM ketanserin and at low PO2, inhibition became noncompetitive. Removal of the endothelium did not influence the action of ketanserin. (vi) Regardless of PO2, the Ca2+ channel antagonist nifedipine (1 microM) significantly inhibited 5-HT- and ET-1-mediated contractions.(ABSTRACT TRUNCATED AT 250 WORDS)

An enzymatic activity in bovine brain that catalyzes the reversal of the C-terminal methyl esterification of protein phosphatase 2A

A novel protein methyltransferase has been recently described that catalyzes the esterification of the C-terminal leucine residue of the catalytic subunit of protein phosphatase 2A in a variety of eucaryotic cells. This reaction can potentially modulate the phosphatase's activity, subunit interactions, or interactions with specific phosphoprotein substrates. We present evidence here that the methylation reaction is reversible and that an enzymatic activity is present in bovine brain cytosol that catalyzes the hydrolysis of the methyl ester. We show that this activity is sensitive to inhibition by the serine-hydrolase inhibitor phenylmethanesulfonyl fluoride but is not affected by the small molecule substrate analog N-acetyl-L-leucine methyl ester. These results suggest that protein methylation and demethylation reactions can be utilized in eucaryotic cells to modulate enzyme activity in a parallel fashion to protein phosphorylation and dephosphorylation reactions.

Characteristics of acupuncture meridians and acupoints in animals

In recent years, an increasing number of studies has been conducted on the biophysical characteristics of the meridians and acupoints in humans and animals. The authors aim to further illustrate the objective existence and superficial locations of the meridians in various species of animals. Twelve sheep, ten goats, thirteen pigs, eleven cats, eight rabbits and seven donkeys were used to measure low impedance lines (LILs) and high percussion sound lines (HPSLs) on the skin surface of the animals, along the vertical planes of the dorsal line, using electrical impulses and high percussion sound. The results of these studies are given.

Molecular phylogenetic studies on Brugia filariae using Hha I repeat sequences

This paper is the first molecular phylogenetic study on Brugia parasites (family Onchocercidae) which includes 6 of the 10 species of this genus: B. beaveri Ash et Little, 1964; B. buckleyi Dissanaike et Paramananthan, 1961: B. malayi (Brug, 1927) Buckley, 1960; B. pahangi (Buckley et Edeson, 1956) Buckley, 1960; B. patei (Buckley, Nelson er Heisch, 1958) Buckley, 1960 and B. timori Partono et al., 1977. Hha l repeat sequences are 322 nucleotides long, highly repeated, tandemly arranged and unique to the nuclear genomes of the genus Brugia. Hha l repeat sequence data was collected by PCR, cloning and dideoxy sequencing. The Hha l repeat sequences were aligned and analyzed by maximum parsimony algorithms, distance methods and maximum likelihood methods to construct phylogenetic trees. Bootstrap analysis was used to test the robustness of the different phylogenetic reconstructions. The data indicated that the Hha l repeat sequences are highly conserved within species yet differ significantly between species. The various tree-building methods gave identical results. Bootstrap analyses on the Hha l repeat sequence data set identified at least two clades: the B. pahangi-B. beaveri clade and the B. malayi-B. timori-B. buckleyi clade; the first clade includes parasites of carnivores from Asia and America; the second includes species from primates and lagomorphs from Asiatic region. It was also noted that the Hha l repeat sequences obtained from B. malayi were identical to those obtained from B. timori, indicating very recent speciation.

[Effect of total coumarins from dried fruits of Cnidium monnieri on glucocorticoid-induced osteoporosis in rats]

Twenty-four 3-month-old male SD rats were divided into 3 groups: Group 1--control (ig water). Group 2--ig prednisone 45 micrograms.kg-1 twice a week. Group 3--treated with total coumarins of dried fruits of Cnidium monnieri (L) Cuss (TCCM) and prednisone. TCCM was given ig 5 g.kg-1, 6 days per week. After 90 d, rats were killed. The proximal tibiae of rats were processed undecalcified for histomorphometric analysis. In comparison with control rats, the bone resorption was enhanced and bone formation decreased. The trabecular bone areas were characterized by reduction of 40% in rats which received prednisone. Trabecular bone areas of rats treated with TCCM increased 56% compared with rats receiving prednisone. All indices of bone histomorphometry were near to those in the control. The results showed that TCCM prevented glucocorticoid-induced osteoporosis.

Molecular phylogenetic studies on filarial parasites based on 5S ribosomal spacer sequences

This paper is the first large-scale molecular phylogenetic study on filarial parasites (family Onchocercidae) which includes 16 species of 6 genera: Brugia beaveri Ash et Little, 1962, B. buckleyi Dissanaike et Paramananthan, 1961; B. malayi (Brug, 1927) Buckley, 1960; B. pahangi (Buckley et Edeson, 1956) Buckley, 1960; B. patei (Buckley, Nelson et Heisch, 1958) Buckley, 1960; B. timori Partono et al, 1977; Wuchereria bancrofti (Cobbold, 1877) Seurat, 1921: W. kalimantani Palmieri. Purnomo, Dennis and Marwoto, 1980: Mansonella perstans (Manson, 1891) Eberhard et Orihel, 1984; loa loc, Stiles, 1905; Onchocerca volvulus (Leuckart, 1983) Railliet er Henry, 1910; O. ochengi Bwangamoi, 1969; O. gutturosa Neumann, 1910; Dirofilaria immitis (Leidy, 1856) Railliet e Henry, 1911; Acanthocheilonema viteae (Krepkogorskaya, 1933) Bain, Baker et Chabaud, 1982 and Litomosoides sigmodontis Chandler, 1931. 5S rRNA gene spacer region sequence data were collected by PCR, cloning and dideoxy sequencing. The 5S rRNA gene spacer region sequences were aligned and analyzed by maximum parsimony algorithms, distance methods and maximum likelihood methods to construct phylogenetic trees. Bootstrap analysis was used to test the robustness of the different phylogenetic reconstructions. The data indicated that 5S spacer region sequences are highly conserved within species yet differ significantly between species. Spliced leader sequences were observed in all of the 5S rDNA spacers with no sequence variation, although flanking region sequence and length heterogeneity was observed even within species. All of the various tree-building methods gave very similar results. This study identified four clades which are strongly supported by bootstrap analysis the Brugia clade; the Wuchereria clade; the Brugia-Wuchereria clade and the Onchocerca clade. The analyses indicated that L. sigmodontis and A. viteae may be the most primitive among the 16 species studied. The data did not show any close relationship between Loa loa and D. immitis presently classified in the same subfamily, and the constitution of the Dirofilariinae subfamily is questionable.

[Cyclocryotherapy for refractory glaucoma after penetrating keratoplasty]

Twenty-eight patients (28 eyes) with secondary glaucoma following penetrating keratoplasty and failed to respond to anti-glaucoma drugs and routine filtering procedures were performed with cyclocryotherapy by nitrogen monoxide. All patients were followed up for more than one year. The results showed intraocular pressure was well controlled in 89% of the eyes, graft remained clear in 85%, and visual functions are preserved in 82% of the patients. Our study suggests that precisely controlled temperature, time, and extent of cryotherapy, and post-operative anti-rejection agents be the key factor to success. Over-treatment, which may lead to atrophy of the eye, must be avoided. It should not be given up flowing under-treatment in the initial procedure.

The effects of streptozotocin diabetes on salivary-mediated bacterial aggregation and adherence

Diabetic rats are known to have an increased susceptibility to dental caries and major alterations in parotid salivary composition. Salivary proteins play an important part in oral health maintenance; thus specific changes in salivary protein composition in diabetic animals might alter the ecological balance in favour of cariogenic bacteria, and toward the initiation and progression of the disease process. The ability of whole, parotid and submandibular salivas from control and streptozotocin-diabetic rats to mediate the aggregation and adherence to hydroxyapatite of mutans streptococci was examined. Salivary-mediated bacterial aggregating activity was significantly reduced in whole and parotid salivas from diabetic rats, but bacterial adherence to hydroxyapatite was unaffected. The aggregating and adherence activities of rat whole saliva were derived mainly from parotid saliva, which contains predominantly low molecular-weight proteins and glycoproteins (< 200 kDa), but rat parotid saliva was capable of interacting with the bacterial receptor for the high molecular-weight aggregating factor in human saliva. SDS-PAGE of parotid saliva revealed that a number of proteins, including the basic and acid proline-rich proteins, were altered in the salivas of diabetic animals. After incubation with either Streptococcus mutans or hydroxyapatite several protein bands were depleted, and thus a variety of proteins and glycoproteins may be responsible for the adherence and aggregating activity of rat parotid saliva.

Endothelium-independent relaxations to acetylcholine and A23187 in the human umbilical artery

The effects of acetylcholine (ACh) and A23187 on ring preparations from the human umbilical artery (HUA) were investigated and compared with the rat aorta (RA). The results from the HUA demonstrate that: (1) At both high (pO2 > 600 mm Hg) and low O2 tension (pO2 < 55 mm Hg), ACh and A23187 relaxed precontracted rings in a concentration-dependent and endothelium-independent manner. Changes in pO2 did not influence the responses of the HUA to either relaxant. (2) Relaxation responses of the HUA to either ACh or A23187 were insensitive to methylene blue (50 microM), L-nitro-arginine methyl ester (100 microM), indomethacin (10 microM) and nordihydroguaiaretic acid (50 microM). Relaxations initiated by ACh were also atropine-resistant. (3) Meclofenamic acid (3 microM) suppressed the relaxations to A23187, but not ACh. (4) Regardless of pO2 superoxide dismutase (100 U/ml) potentiated the relaxant effects of ACh, whereas mannitol (60 mM) enhanced ACh-initiated relaxations at high but not low pO2. (5) Ouabain (30 nM), high potassium (HK+, 60 mM) and tetraethylammonium (20 mM) inhibited responses to ACh. (6) Na(+)-free physiological saline solution inhibited both relaxations and oscillations initiated by either ACh or A23187. (7) Both nitroglycerin and exogenous nitric oxide (NO) fully, and 8-bromoguanosine 3',5'-cyclic monophosphate partially, relaxed the HUA, and LY83583 (10 microM) reversed such relaxations. (8) In the RA, relaxation responses to ACh and A23187 were endothelium-dependent and sensitivity was reduced under high versus low pO2 conditions. We conclude that in the HUA, unlike in the RA, ACh and A23187 mediate their responses via an endothelium- and NO-independent process(es), perhaps involving the release of a muscle-derived relaxing factor. ACh-initiated relaxations are mediated by activation of Na+,K(+)-ATPase, and subsequent hyperpolarization via K+ efflux, whereas A23187-mediated relaxations result from the synthesis of an indomethacin-resistant cyclooxygenase product.

[Improvement of memory function of fornix-fimbria transected rats by transplantation of the superior cervical ganglion into hippocampus]

Memory impairments of passive avoidance response were observed in 38 Wistar rats with bilateral fornix-fimbria transection. After fornix-fimbria lesions the degree of performance decreased from 65.3% to 13.6% (P < 0.01). Autotransplantation of superior cervical ganglion (SCG) into bilateral dorsal hippocampi improved memory function to a considerable extent. In the end of the behavioral experiments, implanted rats were sacrificed for histofluorescence study of grafts and measurement of norepinephrine (NA) content in the hippocampus. These experiments showed that the hippocampal NA content in implanted rats was considerably higher than that in untransplanted fornix-fimbria transected rats and consequently suggested that improvement of memory function was to some extent due to supplement of monoamine transmitter by the transplanted SCG.

Protein phosphatase 2A is reversibly modified by methyl esterification at its C-terminal leucine residue in bovine brain

We have recently described a novel protein carboxyl methylation system that results in the reversible modification of a 36-kDa polypeptide component of a 178-kDa protein in the cytosol of a variety of eucaryotic cells. This reaction, catalyzed by a cytosolic 40-kDa methyl-transferase, results in the methyl esterification of the alpha-carboxyl group of the C-terminal leucine residue. We have now purified the major methylated 36-kDa polypeptide from bovine brain. N-terminal sequence analysis of a tryptic fragment of this polypeptide revealed identity to the catalytic subunit of protein phosphatase 2A. This enzyme exists in the cell predominantly as a trimeric 151-kDa native species containing the 36-kDa catalytic polypeptide that terminates in a leucine residue. We then fractionated bovine brain cytosolic extracts to separate the major phosphatase isoforms 2A1 and 2A2 and found that both could be methylated by a partially purified preparation of the methyltransferase. A synthetic C-terminal octapeptide based on the sequence of the 36-kDa catalytic subunit is neither a substrate nor an inhibitor of this methyltransferase, suggesting that this enzyme recognizes aspects of the tertiary and/or quaternary structure of the native phosphatase. Because this modification reaction is readily reversible in extracts, it may represent a novel strategy of the cell to modulate the function of this protein phosphatase.