[The influence of Millard-lip-repair on maxillary growth: an experiment study in rabbits]

OBJECTIVE

To study the effects of the cheiloplasty(Millard rotation-advancement lip-repair) on the maxillary growth.

METHODS

Thirty Japanese white rabbits were randomly divided into three groups, Group I (unoperated control group), Group II (unrepaired control group) and Group III (repaired with Millard-lip-repair). All the animals were sacrificed and measured on the clean slulls directly at 26 weeks postoperatively (30 weeks old).

RESULTS

It was found that Group III (Millard repair group) had the anterioposterior growth disturbance of maxilla than Group I and II, while the height of maxilla and width of posterior dental arch were larger than that of the two control groups for compensation, and the nasal septum of Group III deviated to the cleft side.

CONCLUSION

Millard-rotation-advancement lip-repair operation has inhibitory effects on maxillary growth.

Nitric oxide synthesis inhibition modifies the cardiotoxicity of tetracaine and lidocaine

Suppression of nitric oxide (NO) production alters the toxicity of cocaine and bupivacaine. We undertook this study to determine whether the systemic toxicity of two other local anesthetics that differ in antiarrhythmic activity, plasma clearance, and biotransformation are similarly affected by nitric oxide synthase (NOS) inhibition. Sprague-Dawley rats anesthetized with 70% N2O and 0.5% halothane mixed with O2 were pretreated with saline (0.2 mL x kg(-1) x min(-1) i.v.) or N(omega)-nitro-L-arginine methyl ester (L-NAME; a competitive inhibitor of NOS) (2 mg x kg(-1) x min(-1) i.v.) for 30 min. The animals were then given tetracaine (3 mg x kg(-1) x min(-1) i.v.) or lidocaine (8 mg x kg(-1) x min(-1) i.v.) until cardiac arrest (asystole). Doses of lidocaine or tetracaine that produced arrhythmias, seizures, isoelectric encephalogram, and asystole were determined. Hemodynamic recordings were performed throughout the experiments, and plasma was collected to measure the concentration of lidocaine or tetracaine. L-NAME decreased tetracaine and lidocaine doses that produced arrhythmias (> or = 2 degrees atrioventricular conduction block) (tetracaine 14 +/- 2 mg/kg; lidocaine 102 +/- 9 mg/kg) versus saline treatment (tetracaine 28 +/- 2 mg/kg; lidocaine 136 +/- 9 mg/kg; P < 0.05). The tetracaine and lidocaine doses required to produce asystole were also smaller in animals with L-NAME pretreatment than those in saline-pretreated animals. L-NAME reduced the arrhythmia dose of tetracaine more than the arrhythmia dose of lidocaine (28 of 14 = 2.0 fold and 136 of 102 = 1.3-fold). The plasma concentration of lidocaine, but not tetracaine, was significantly higher at each sample time in L-NAME-pretreated animals than in saline-pretreated animals. Inhibition of NOS by L-NAME enhances the cardiotoxicity of lidocaine and tetracaine, with a greater effect on tetracaine than on lidocaine. Altered drug clearance by L-NAME was insufficient to explain these findings because L-NAME pretreatment increased the plasma levels of only lidocaine, not tetracaine.

IMPLICATIONS

Inhibition of nitric oxide production in rats markedly enhances the cardiovascular toxicity of lidocaine and tetracaine. Altered drug clearance by N(omega)-nitro-L-arginine methyl ester was insufficient to explain these findings because N(omega)-nitro-L-arginine methyl ester pretreatment increased the plasma levels of only lidocaine, not tetracaine.

Apoptosis induced by infection of primary brain cultures with diverse human immunodeficiency virus type 1 isolates: evidence for a role of the envelope

Apoptosis of neurons and astrocytes is induced by human immunodeficiency type 1 (HIV-1) infection in vitro and has been demonstrated in brain tissue from patients with AIDS. We analyzed a panel of diverse HIV-1 primary isolates for the ability to replicate and induce neuronal and astrocyte apoptosis in primary human brain cultures. Apoptosis was induced three- to eightfold by infection with the blood-derived HIV-1 isolates 89.6, SG3, and ADA. In contrast, the brain-derived HIV-1 isolates YU2, JRFL, DS-br, RC-br, and KJ-br did not induce significant levels of apoptosis. The ability of HIV-1 isolates to induce apoptosis was independent of their replication capacity. Studies of recombinant chimeras between the SG3 and YU2 viruses showed that replacement of the YU2 Env with the SG3 Env was sufficient to confer the ability to induce apoptosis to the YU2 virus. Replacement of the Env V3 regions alone largely conferred the phenotypes of the parental clones. The SG3 Env used CXCR4 and CCR3 as coreceptors for virus entry, whereas YU2 used CCR5 and CCR3. The V3 regions of SG3 and YU2 conferred the ability to use CXCR4 and CCR5, respectively. In contrast, the 3' region of Env, particularly the C3V4 region, was required in conjunction with the V3 region for efficient use of CCR3. These results provide evidence that Env is a major determinant of neurodegenerative mechanisms associated with HIV-1 infection in vitro and raise the possibility that blood-derived viruses which emerge during the late stages of disease may affect disease progression in the central nervous system.

Two genetically selected strains of rats exhibit hypersensitivity or resistance to cocaine-induced fatal arrhythmias

We identified for the first time two genetically selected strains of rats that differ markedly in sensitivity to cocaine-induced life-threatening cardiac arrhythmias and arrest. The two strains of rats, designated as Fast and Slow, were bred for sensitivity (Fast) or resistance (Slow) to electrically kindled seizures. Studies were performed on halothane-anesthetized, mechanically ventilated rats. Animals were given cocaine (3 or 4 mg/kg/min i.v.) until they died. Arrhythmias (atrioventricular conduction block) developed at much lower cumulative cocaine doses in Slow-kindling rats than in Fast-kindling rats (15 +/- 1 versus 42 +/- 3 mg/kg, p <.01). The lethal cocaine dose (the dose that caused cardiac arrest) was also markedly lower in Slow than in Fast strains (32 +/- 2 versus 62 +/- 6 mg/kg, p <.01). These differences between the two strains were not significantly altered by pretreatment of animals with either ganglionic blockers, hexamethonium (20 mg/kg i.v.) or chlorisondamine (5 mg/kg i.v.), or a nonselective beta adrenergic receptor blocker, propranolol (1 mg/kg i.v.). A nonselective alpha adrenergic receptor blocker, phentolamine (10 mg/kg i.v.), however, abolished the differences between the Fast and Slow strains in the doses of cocaine required to produced atrioventricular conduction block and cardiac arrest. The results provide the first evidence of genetically determined susceptibility or resistance to cocaine-induced cardiotoxicity. There appears to be a genetically determined difference in the alpha adrenergic receptor system between the two strains that is responsible for the differential sensitivity to cocaine-induced arrhythmias and cardiac arrest.

Identification and characterization of baxepsilon, a novel bax variant missing the BH2 and the transmembrane domains

The Bax gene is a member of the Bcl2 family that functions to regulate the programmed cell death process. A number of Bax isoforms have been previously identified: alpha, beta, gamma, delta, and omega. Here we report the identification and characterization of an additional Bax variant, termed Baxepsilon. The newly identified Bax variant contains a 97-base insertion generated by alternative splicing which includes a previously unidentified exon between exons 4 and 5. The insertion causes the production of a truncated Bax protein, termed Baxepsilon, which encodes a protein of 164 residues with a calculated molecular weight of 18 kDa. The last 69 amino acids of Baxalpha that encompass the BH2 and the TM domains are missing in Baxepsilon. The Baxepsilon protein, when expressed as a GST fusion protein, associated efficiently with Baxalpha, Baxepsilon, Bcl2, and Bcl-xL. In addition, Baxepsilon was active in inducing apoptosis when tested in a transient transfection assay. Furthermore, the presence of antiapoptotic genes including Bcl2, Bcl-xL, and baculovirus p35 abrogated Baxepsilon and Baxalpha function. Although the newly identified Bax variant was detectable by RT-PCR in several normal mouse tissues, the role of this variant in controlling programmed cell death is currently unknown.

Dexamethasone induces hypertrophy of developing medial septum cholinergic neurons: potential role of nerve growth factor

Glucocorticoid hormones influence neuronal plasticity during development; however little is known about the mechanisms of this trophic activity. Because glucocorticoids increase nerve growth factor (NGF) synthesis in selected brain areas and NGF plays a role in the development of basal forebrain cholinergic neurons, we tested the hypothesis that glucocorticoids may foster maturation of the cholinergic phenotype during postnatal development via the induction of NGF biosynthesis. The synthetic glucocorticoid dexamethasone (DEX) was injected systemically (0.5 mg/kg, s.c.) once a day for 1 week in 7-d-old (P7) rats. DEX elicited an increase in NGF mRNA and protein levels in the cerebral cortex and hippocampus as well as specific NGF responses, such as TrkA tyrosine phosphorylation in the septum, choline acetyltransferase (ChAT) and p75 neurotrophin receptor (p75NTR) immunoreactivity, and a relative number of cholinergic neurons in the medial septum. To examine whether the effect of DEX is age-related, we treated 1- and 14-d-old rats with DEX for 1 week. DEX increased NGF expression in rats treated from P1 to P8 but not in those treated from P14 to P21. The age-related increased expression of NGF correlated with the induction of ChAT immunoreactivity in the medial septum. Moreover, in the spinal cord, neither NGF nor ChAT levels were increased by DEX, suggesting that the glucocorticoid-mediated changes seen in the basal forebrain are associated with specific NGF responses. Our data suggest that by increasing NGF levels, glucocorticoids may play a role in the maturation of postnatal cholinergic neurons.

[Application of stress urethral pressure profile for diagnosis and treatment of stress incontinence]

OBJECTIVE

To apply the stress urethral pressure profile (SUPP) to diagnose the genuine stress incontinence (GSI) and to evaluate the results of treatment.

METHOD

22 patients with GSI underwent SUPP and rest urethral pressure profile (RUPP) using Dantec Menuet.

RESULT

The results showed that the pressure transmission ratio (PTR) was 0.68 +/- 0.06, and urethral close pressure (UCP) was -0.62 +/- 0.22 kPa in 22 patients. PTR and UCP raised significantly after operation in 5 patients, P < 0.01. The results of SUPP were compared with those RUPP.

CONCLUSION

SUPP is important in both diagnosis and evaluation of GSI, although some limitation exists. To improve the level of diagnosis, it should be combined with other method in clinical use.

Cocaine cardiotoxicity differs markedly in isolated hearts of two strains of rats exhibiting phenotypic differences in sensitivity to seizures

Isolated hearts from two strains of rats bred for sensitivity or resistance to amygdala kindling that also exhibit, in vivo, differential sensitivity to the cardiotoxicity of cocaine were studied. The goal was to determine if the differential cardiotoxic sensitivity was due, at least in part, to intrinsic strain-dependent differences in the heart. The Langendorff preparation was used (n=8 per strain). Hearts were perfused with increasing concentrations of cocaine (5 x 10(-6), 1 x 10(-5), 5 x 10(-5), 1 x 10(-4), and 5 x 10(-4) M) for 5 min with a 5 min washout between exposure to successive concentrations. Consistent with in vivo observations, hearts from genetically slow amygdala kindling rats (Slow) required lower cocaine doses to develop cardiac arrhythmias and arrest as compared to the hearts from genetically fast amygdala kindling rats (Fast). At 5 x 10(-5) M cocaine arrhythmias occurred in 38% (3/8) Slow and 0% Fast hearts. Five of 8 Slow hearts and none of 8 Fast hearts were arrested by 10(-4) M cocaine. Arrest in Fast hearts occurred only with 5 x 10(-4) M cocaine. Cocaine constricted coronary arteries (no significant difference between strains). On the other hand, coronary arteries of Slow but not Fast hearts dilated during cocaine washout after perfusion with all but the highest concentration of cocaine. We conclude that factors intrinsic to the heart and coronary artery influence the sensitivity or response of these structures to cocaine.

Neuronal apoptosis induced by HIV-1 Tat protein and TNF-alpha: potentiation of neurotoxicity mediated by oxidative stress and implications for HIV-1 dementia

Apoptosis of neurons and non-neuronal cells has been demonstrated in the brain of AIDS patients with dementia. Previous studies suggest that the apoptotic stimuli are likely to be soluble factors. Several candidates for the soluble factors that lead to neuronal apoptosis in HIV-1 infection have been proposed, including the HIV-1 Tat protein and TNF-alpha. The mechanisms that lead to neuronal apoptosis in the brain of AIDS patients in vivo, may involve the combined effects of more than one pro-apoptotic factor. In this study, we examine whether exposure of primary human neurons to the combination of HIV-1 Tat and TNF-alpha can potentiate the induction of neuronal apoptosis compared with exposure to either factor alone. TNF-alpha was shown to potentiate the induction of neuronal apoptosis by HIV-1 Tat via a mechanism that involves increased oxidative stress. Antioxidants inhibited, but did not completely abolish the induction of neuronal apoptosis by Tat, suggesting that other mechanisms are also likely to be involved. These findings suggest that soluble HIV-1 Tat and TNF-alpha may play a role in neuronal apoptosis induced by HIV-1 infection of the CNS, particularly when present in combination. Our findings further suggest that one mechanism whereby combinations of pro-apoptotic factors may potentiate the induction of neuronal apoptosis in the brain of AIDS patients is by increasing oxidative stress. Understanding the role of oxidative stress and other mechanisms that lead to apoptosis in HIV-1 infection of the CNS may advance the development of new therapeutic strategies to prevent neuronal cell death and improve neurologic function in AIDS patients.

[Treating portal hypertension by subtotal splenectomy with retroperitoneal splenic transposition and devascularization: clinical study]

OBJECTIVE

To devise a new surgical procedure for improving the operative effect of portal hypertension caused by hepatic cirrhosis.

METHOD

In treatment group, subtotal splenectomy with retroperitoneal transposition was performed in 36 patients of cirrhotic hypertensives. In control group, 36 patients were treated by devascularization. The follow-up period ranged from 3 months to 5.5 years (average 26 months).

RESULT

In the treatment group, the rates of disappearance, improvement and absence of changes of esophageal varices were 11.5%, 61.5% and 26.9%, respectively, and in the control group those of improvement were 50.0%, absence of change 45.8% and aggravation 4.2%. There was a significant difference between them (P < 0.05). In the treatment group, hypersplenism disappeared in all. There was also significant difference between the two groups in immunological indexes (P < 0.05). DSA showed abundant collateral circulation in the residual spleen and retroperitoneal wall, which enabled the portal blood flow diverting to retroperitoneal tissues.

CONCLUSION

This method possesses the advantages of devascularization and decompression shunt. It is of value in retaining part of spleen in surgical treatment of portal hypertension.

[Isoharringtonine induces apoptosis in human leukemia HL-60 cell]

Harringtonine (HT), homoharringtonine (HHT) and isoharringtonine (IHT) are cephalotaxine alkaloids with anticancer activities which were isolated from Cephalotaxus hainanensis indigenous to China. Since the 1970s, HT and HHT have been developed as effective anticancer drugs in China and have been used widely in the treatment of acute nonlymphoid leukemia and chronic granulocyte leukemia. Although IHT has the advantage of low toxicity, it has not been developed as an anticancer drug because of its very low content in the plant. The cell apoptosis induced by isoharringtonine was investigated in human acute promyelocytic leukemia HL-60 cells by agarose gel electrophoresis of DNA, flow cytometry and transmission electron microscopy. In these experiments IHT showed significant and rapid apoptotic inductive effect on HL-60 cells in both concentration- and time-dependent fashion. The characteristic apoptosis-related features could be seen in IHT treated HL-60 cells. Transmission electron microscopy of IHT treated HL-60 cells displayed chromatin condensation and aggregation under the nuclear membrane, nuclear fragmentation and apoptosis body formation. Typical DNA ladder in agarose gel electrophoresis and pre-G1 peak in flow cytometric analysis were also observed in the cells exposed to IHT. The apoptotic rate could reach 43.8% in the HL-60 cells treated for 120 minutes with IHT 10(-7) mol.L-1. The cytotoxicity of IHT paralleled with cell apoptosis indicating that the anticancer activity of IHT results from the induction of apoptosis. These results are important impetus for further research and development of IHT as an anticancer agent.

[The influence of implantal autograft bone in total cleft palate on maxillary growth an experiment study in dogs]

OBJECTIVE

To test the hypothesis that implant autograft bone in total cleft palate at primary cleft palate repair which may resists the disturbance of maxillary growth by cleft and denud bony wound.

METHODS

40 dogs were randomly divided into four groups: three control groups and one experimental group. The first control group was unoperated, the second group had a surgically created cleft plate, the third group also had a surgically created cleft palate. Using a two-flap procedure immidiately, the experiment group had a surgically created cleft palate, but the palate was recontracted by implanting a piece of autograft rib bone with two-flap repair. All animals were sacrificed on the 34th week after operation (43 weeks postnatal). Thirty-four metricranial variables were measured directy from the cleaned skulls.

RESULTS

The method is useful for maxillary growth and development by bone implant in total cleft palate, but it can cause maxillary deformity.

CONCLUSION

Clinical doctors should be cautious in using the method of primary-delay bone grafting in reparing total cleft of cleft palate.

Evidence for a role of bradykinin neurons in the control of gonadotropin-releasing hormone secretion

The present study provides evidence of a novel neuronal pathway for the control of GnRH secretion involving bradykinin neurons. Bradykinin neurons were shown by immunohistochemistry to be densely localized in several regions of the brain including the cortex, hippocampus and supraoptic nucleus, as well as two regions critical in the control of GnRH secretion, the organum vasculosum of the lamina terminalis and arcuate nucleus. Bradykinin dose-dependently stimulated GnRH release from male and proestrous female rat hypothalami in vitro. Antagonist studies revealed that bradykinin effects are mediated by the bradykinin B2 receptor. The effect of bradykinin on GnRH release is not mediated by the classical major transmitter, glutamate, as glutamate antagonists had no effect on bradykinin stimulation of GnRH release. Rather, bradykinin appears to act directly on the GnRH neuron as bradykinin stimulated GnRH release directly from immortalized GnRH (GT1-7) neurons in vitro, and immunoblot studies revealed that the bradykinin B2 receptor is present in GT1-7 neurons. The bradykinin B2 receptor was also demonstrated in the rat hypothalamus and pituitary by immunoblotting. Bradykinin-induced exocytosis of GnRH appears to involve activation of the PKC signaling pathway, as a PKC inhibitor blocked bradykinin-induced GnRH release. Finally, bradykinin neurons appear to be important mediators of steroid signals in the hypothalamus to produce the LH surge, as central administration of a B2 antagonist, but not a B antagonist, significantly attenuated the steroid-induced LH surge in the ovariectomized female rat.

[Study on urinary levels of interleukin-1 beta, interleukin-6 and tumor necrosis factor-alpha in patients with renal cell carcinoma]

We examined the preoperative and postoperative, urinary levels of the cytokines, interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) in 14 patients with renal cell carcinoma (RCC), and 9 patients who underwent nephrectomy as donors (controls). Although urinary IL-1 beta was measurable in every subject, both IL-6 and TNF-alpha were undetectable in 12 of the 14 patients. None of the urinary cytokines showed levels significantly different from the controls preoperatively. Urinary levels of IL-1 beta showed no correlation with clinical stage or histological grade. Only urinary IL-1 beta was significantly elevated after nephrectomy, when compared with the controls (P < 0.05). However, urinary IL-1 beta showed no correlation with operative blood loss or postoperative infection. These findings suggest that measurement of urinary cytokines is not useful for diagnosis or monitoring of therapy in RCC patients.

[Determination of copper, zinc, iron and calcium in wheat and maize and three nitrogen compounds in high and low risk areas of esophageal cancer]

This study reports the concentrations of copper, zinc, iron and calcium in wheat and maize from high risk area Linzhou and low risk area Yuzhou of esophageal cancer and three nitrogen compounds of four types of drinking water in Linzhou. The results showed that the concentrations of zinc and calcium in wheat and maize from Linzhou were significantly lower than these from Yuzhou, the copper concentrations in grains were higher and the iron in maize was lower. The nitrate-N concentrations in four types of drinking water from Linzhou were below the national standard but the nitrite and NH3-N concentrations were higher than the national limits. The results suggest that the low concentrations of zinc, iron and calcium and high concentrations of copper in grains as well as the high concentrations of nitrite and NH3-N may be related to the etiology of esophageal cancer.

Experimental studies of electroacupuncture on ventricular fibrillation threshold in rats with acute ischemic myocardium

By ligating the proximate left anterior descend (LAD) of coronary artery and inducing the ventricular fibrillation with electrical stimulation, the preventive effects of electroacupuncture (EA) on ventricular fibrillation were observed. The results showed that the ventricular fibrillation threshold (VFT) of rats with acute ischemic myocardium was raised after acupuncturing some acupoints, which could prevent the occurrence of ventricular fibrillation. Furthermore, the combination of EA and propranolol could enhance the VFT effectively, and they showed a good synergistic effect.

Localization of HIV-1 co-receptors CCR5 and CXCR4 in the brain of children with AIDS

The chemokine receptors CCR5 and CXCR4 are co-receptors together with CD4 for human immunodeficiency virus (HIV)-1 entry into target cells. Macrophage-tropic HIV-1 viruses use CCR5 as a co-receptor, whereas T-cell-line tropic viruses use CXCR4. HIV-1 infects the brain and causes a progressive encephalopathy in 20 to 30% of infected children and adults. Most of the HIV-1-infected cells in the brain are macrophages and microglia. We examined expression of CCR5 and CXCR4 in brain tissue from 20 pediatric acquired immune deficiency syndrome (AIDS) patients in relation to neuropathological consequences of HIV-1 infection. The overall frequency of CCR5-positive perivascular mononuclear cells and macrophages was increased in the brains of children with severe HIV-1 encephalitis (HIVE) compared with children with mild HIVE or non-AIDS controls, whereas the frequency of CXCR4-positive perivascular cells did not correlate with disease severity. CCR5- and CXCR4-positive macrophages and microglia were detected in inflammatory lesions in the brain of children with severe HIVE. In addition, CXCR4 was detected in a subpopulation of neurons in autopsy brain tissue and primary human brain cultures. Similar findings were demonstrated in the brain of adult AIDS patients and controls. These findings suggest that CCR5-positive mononuclear cells, macrophages, and microglia contribute to disease progression in the central nervous system of children and adults with AIDS by serving as targets for virus replication.

Intracellular calcium oscillations in cell populations of ras-transfected I-7 subline of human HaCaT keratinocytes

We have observed oscillations of intracellular Ca2+ (Ca[i]) concentration in populations of ras-transfected HaCaT keratinocytes of I-7 subline. In postconfluent monolayers of I-7 keratinocytes, an increase in extracellular Ca2+ (Ca[o]) concentration to 0.25-0.5 mM induced sinusoidal Ca(i) oscillations, which persisted longer than 1 h with amplitudes of 50-150 nM and periods of 5-10 min. Thapsigargin, which depletes internal Ca2+ stores, did not prevent Ca(o)-induced Ca(i) oscillations, and it also induced Ca(i) oscillations in the ras-transfected I-7 line. Removal of extracellular Ca2+ or addition of Ca2+-entry blocker La3+ or SK&F 96365 inhibited Ca(i) oscillations, suggesting that Ca(i) oscillations in ras-transfected HaCaT keratinocytes were dependent on Ca2+ influx across the plasma membrane. Because the Ca(o)-induced Ca(i) oscillations have been observed only in ras-transfected I-7 subline and not in its nontransfected parental HaCaT line, this may provide a partial explanation for the divergent responses of ras-transfected and nontransfected keratinocytes to Ca(o) signal for control of growth and differentiation.

Babesiasis in Nanjing area, China

This article discusses the tick-borne babesiases which harm dairy cattle, buffaloes and dogs. In addition, the pathogen, vector, seasonal occurrence, hosts, symptoms, pathological changes and treatment are summarized and analysed. The pathogens in this area were identified as Babesia bigemina, B. bovis and B. gibsoni; the vectors as Boophilus microplus, Rhipicephalus haemaphysaloides, Haemaphysalis longicornis. Affected buffaloes were found from April to September, peak numbers occurred between May and July. Affected dairy cattle were most numerous in July and August. Hunting dogs were the most affected dogs. Infected dogs were found from February until the beginning of December; peak numbers occurred from September to November. Affected animals were acute cases. Symptoms and pathological changes were obvious, but jaundice was rare in dogs. Acaprin, acriflavine, imidocarb and berenil were used early and late. Their effect was ideal but resistance has developed to these drugs.

[Inhibitory effect of samarium-153-labeled ethylenediaminetetramethylene phosphonate (EDTMP) on bone invasion and osteolysis in Walker 256 carcinoma bearing rats]

OBJECTIVE

To investigate the inhibitory effect of samarium-153 EDTMP on bone invasion and osteolysis in Walker 256 carcinoma bearing rats.

METHODS

Invasion and resorption of tibia by Walker 256 carcinoma in rats were evaluated by X-ray and histological examination.

RESULTS

Intravenous administration of 153Sm-EDTMP at a dose of 74 or 148 MBq/kg, the rat numbers with tibia invasion and bone resorption were reduced by fifty percent. 153Sm-EDTMP at a dose of 37 MBq/kg still exhibited inhibitory effect on bone invasion and osteolysis as compared with the control group. However, there was no indication of change in the weight of primary tumor even at the highest dose utilized.

CONCLUSION

Samarium-153 EDTMP can inhibit bone invasion and osteolysis by Walker 256 carcinoma in rats, but it has no effect on the growth of the transplanted tumor. Therefore, that the effect of 153Sm-EDTMP is due to a reduction in tumor growth leading to decreased bone invasion and osteolysis can be reasonably ruled out.

Tat protein induces self-perpetuating permissivity for productive HIV-1 infection

We report that human immunodeficiency virus type 1 (HIV-1) has evolved a self-perpetuating mechanism to actively generate cells permissive for productive and cytopathic infection. Only activated T cells can be productively infected, which leads to their rapid depletion (2 x 10(9)/day in an infected individual). Establishment of productive HIV-1 infection therefore requires continual activations from the large pool of quiescent T cells. Tat protein, which is secreted by infected cells, activated uninfected quiescent T cells in vitro and in vivo. These Tat-activated uninfected cells became highly permissive for productive HIV-1 infection. Activation of primary T cells by Tat protein involved integrin receptors and was associated with activation of mitogen-activated protein kinases, including ERK1 and JNK kinase. Accordingly, these primary T cells progressed from G0 to the late G1 phase of the cell cycle.

Bioavailability of selenium from veal, chicken, beef, pork, lamb, flounder, tuna, selenomethionine, and sodium selenite assessed in selenium-deficient rats

The bioavailability of selenium (Se) from veal, chicken, beef, pork, lamb, flounder, tuna, selenomethionine (SeMet), and sodium selenite was assessed in Se-deficient Fischer-344 rats. Se as veal, chicken, beef, pork, lamb, flounder, tuna, SeMet, and sodium selenite was added to torula yeast (TY) basal diets to comprise Se-inadequate (0.05 mg Se/kg) diets. Se as sodium selenite was added to a TY basal diet to comprise a Se-adequate (0.10 mg Se/kg), Se-control diet. The experimental diets were fed to weanling Fischer-344 rats that had been subjected to dietary Se depletion for 6 wk. After 9 wk of the dietary Se repletion, relative activity of liver glutathione peroxidase (GSHPx) from the different dietary groups compared with control rats (100%) was: flounder 106%, tuna 101%, pork 86%, sodium selenite 81%, SeMet 80%, beef 80%, chicken 77%, veal 77%, and lamb 58%. Se from flounder was the most efficient at restoring Se concentrations in the liver and skeletal muscle. Se from sodium selenite, SeMet, beef, veal, chicken, pork, lamb, and tuna was not dietarily sufficient to restore liver and muscle Se after 9 wk of recovery following a 6-wk period of Se depletion.

[Deviation of size-exclusion chromatographic behavior of tryptophan on TOYOPEARL HW-40S column]

A deviation of size-exclusion chromatographic behavior of amino acids on TOYOPEARL HW-40S column is reported. On the column 18 amino acids were not eluted in the same fraction in the total volume, but separated into 5 fractions with tryptophan as the last one far behind the total volume. Interaction between tryptophan and the matrices was investigated under different conditions in order to elucidate the chemical nature of the deviation. It was found that addition of trifluoroacetic acid and sodium chloride of high concentration in mobile phase, dramatically increased the retention time of trypophan, while addition of acetonitrile, sodium chloride of lower concentration and the hydrogen bond breaker urea reduced the interaction. It is concluded that adsorption of tryptophan on TOYOPEARL HW-40S is basically due to the hydrophobic nature with limited influence of hydrogen bond and ionic interaction. The former factor can be eliminated by keeping acentonitrile concentration over 50% (V/V), while the latter two can be reduced to the minimum by adding 0.17mol/L sodium chloride and 3.51mol/L urea. The results not only lead to better understanding of size-exclusion chromatography of this matrices, but also help to apply hydrophobic chromatography of this matrices to the isolation of amino acids and peptides.

[4-acetamidophenyl retinoate (4-APR) inhibits reconstituted basement membrane invasion by tumor cells and its mechanism]

OBJECTIVE

To study the inhibitory effect of new retinoid 4-acetamidophenyl retinoate (4-APR) on the reconstituted basement membrane invasion by B16-F10 mouse melanoma cells and its mechanism.

METHODS

Reconstituted basement membrane invasion assay was used to evaluate invasive ability of cancer cells. Type IV collagenase was assessed by PAGE substrate zymography. TIMP-1 mRNA expression of human nasopharyngeal carcinoma CNE-2Z cell line was measured by dot blot analysis. Cell growth curve assay was used to examine the growth inhibitory effect of 4-APR on B16-F10 cells.

RESULTS

4-APR, at the concentrations of 10(-5) mol/L and 10(-6) mol/L, suppressed the reconstituted basement membrane invasion of B16-F10 mouse melanoma cells by 54.2%, 41.9% and reduced type IV collagenase activities in the serum-free supernatant of CNE-2Z cells. In addition, 4-APR inhibited B16-F10 cell adherence to laminin, fibronectin and Matrigel, and induced CNE-2Z cell TIMP-1 mRNA expression.

CONCLUSION

Reconstituted basement membrane invasion of B16-F10 mouse melanoma cells was inhibited by 4-APR. The anti-invasion action of 4-APR might be associated with the suppression of tumor cell adhesion ability, the reduction of type IV collagenase activity in tumor cell culture supernatant and/or the induction of tumor cell TIMP-1 mRNA expression.

[An experimental study of the growth pattern and mechanisms of surgically induced cleft palate and palatoplasty on maxillary growth in dogs]

The authors observed the changing process of length, width and height of maxillary growth in experimental animals, the experimental animals were divided into the unoperated control group, the surgical induced cleft palate group, the repaired cleft palate group and the group of implanted autograft bone in total hard palate. The method of a serial dorsoventral and lateral cephalograms were used in the study. The experimental result showed: the rate of maxillary growth began to change from two to four weeks and finished in the eighteenth week after operation. There was a remarkable different rate of maxillary growth among the four groups. The track of premaxillary growth had a difference between unoperated control group and the others. The experimental result suggested that the direction of growth in nasal septal cartilage and the conduction of force from premaxillary to maxillary were inhibited. It is a main reason for maxillary growth disturbance of the cleft palate who had or had not surgery.

[An experimental study of the influence and mechanism of surgically induced cleft palate and palatoplasty on teeth and dental arch in dogs]

The dogs were selected as the experimental subjects in this study. The authors continuously observed the maxillary teeth and dental arch form in preoperation and 2, 4, 6, 10, 14, 18, 22, 26, 30, 34 weeks of post operation to all the animals. 40 puppies were divided into four groups, which were unoperated control group, surgically induced cleft palate group, cleft palate repaired group and cleft palate implanted bone group. The experimental result showed: there were remarkable differences at rate of itself growth between deciduous dentition and permanent dentition in the four groups. The result suggested that the cleft palate was a reason for disturbances of dental arch development, an exposed bone wound in hard palate of maxillary after palatoplasty was an important reason that it made maxillary dental arch growth problem heavier, authors could prevent the disturbs the transverse development of the maxillary dental arch from cleft palate who had or had not repaired by implanted bone in total cleft palate.

Modification of bupivacaine toxicity by nonselective versus neuronal nitric oxide synthesis inhibition

We have previously shown that pretreatment of rats with a nonselective nitric oxide synthase (NOS) inhibitor, N(omega)-nitro-L-arginine methyl ester (L-NAME), enhances the cardiovascular system (CVS) toxicity and reduces the central nervous system (CNS) toxicity of local anesthetics. This study was performed to differentiate the neuronal from the endothelial effects of L-NAME on the CNS and CVS toxicity of bupivacaine by comparing the effects of L-NAME with a neuronal selective NOS inhibitor, 7-nitroindazole (7-NI). Lightly anesthetized rats were premedicated for 30 min with L-NAME (2 mg kg(-1) x min(-1) intravenously [I.V.]), 7-NI (30 mg/kg intraperitoneally), or saline (control) then bupivacaine (2 mg x kg(-1) x min(-1)) was infused I.V. until asystole occurred. Bupivacaine doses required to produce seizures were the same among groups (saline = 10.1 +/- 2.6 mg/kg; L-NAME = 9.0 +/- 1.2 mg/kg; 7-NI = 10.2 +/- 1.0 mg/kg). However, plasma bupivacaine concentration (microg/mL) at seizure onset was significantly higher in animals pretreated with L-NAME (16.4 +/- 2.1) and, to a lesser degree, 7-NI (11.6 +/- 1.3) than that of control (9.7 +/- 1.6). Seizure duration and the number of epileptiform bursts were significantly reduced in L-NAME versus the other two groups. Doses for arrhythmias and asystole as well as plasma bupivacaine concentrations at arrhythmia onset were dramatically smaller in L-NAME-pretreated rats than in the other two groups. In summary, endothelial NOS inhibition dramatically alters both the CVS and CNS toxicity of bupivacaine with neuronal NOS inhibition playing a minor role.

A four-amino-acid insertion in the ligand-binding domain inactivates hRXRbeta and renders dominant negative activity

Retinoid X receptors (RXRs) are members of the steroid and thyroid hormone receptor superfamily of hormone-dependent transcription factors that mediate the pleiotropic effect of retinoids. Here, we report the initial characterization of an isoform of hRXR beta, termed hRXR beta3, which was previously identified as an H-2RIIBP isoform (Epplen and Epplen, 1992). The hRXR beta3 isoform cotains an in-frame insertion of four amino acids (SLSR) in the ligand binding domain at codon 419. The isoform is generated by alternate use of a 3' splice acceptor site and was detectable by reverse transcription polymerase chain reaction (RT-PCR) in all human tumor cell lines and mouse tissues examined. Chimeric receptors, in which the ligand-binding domain of hRXR alpha was substituted by the corresponding domain from hRXR beta3, were used to investigate the consequences of the SLSR insertion on the transactivation and DNA-binding functions of the chimeric receptor. Co-transfection assays revealed that a chimera RXR alpha/beta3 receptor failed to transactivate the RXR-specific CRBPII promoter, whereas the identical chimera lacking the SLSR insertion was active. The RXR alpha/beta3 receptor exhibited dominant negative activity against active retinoid X and retinoic acid receptors on retinoid-responsive promoters. Moreover, the RXR alpha/beta3 protein failed to interact physically with the retinoic acid receptor (RAR) to form heterodimers as detected by physical association assays, and failed to bind DNA containing an RAR-responsive element. Therefore, this suggests that the SLSR insertion in the ligand-binding domain of the RXR alpha/beta3 receptor is responsible for the altered behavior of the chimera. Our findings raise the possibility that RXR alpha/beta3, and perhaps hRXR beta3 isoform, function by titrating a limiting adaptor molecule that is involved in mediating retinoid function.

Two novel subgenomic RNAs derived from RNA 3 of tomato aspermy cucumovirus

Two abundant subgenomic RNAs, designated RNA 3B and RNA 5, were found to be associated with the V strain of tomato aspermy cucumovirus (V-TAV). Sequence determination showed that the 3'-terminal 323 nucleotides (nt) of RNA 3B was identical to RNA 5, whereas its 5'-terminal 163 nt was a direct repeat (one nt difference) of the 5'-half of RNA 5, and that both RNAs are completely homologous to the 3'-terminal untranslated region of TAV RNA 3. TAV RNAs 3B and 5 were also detected in the infection of a pseudorecombinant virus consisting of TAV RNA 3 and RNAs 1 and 2 from cucumber mosaic virus. Furthermore, only RNA 5, not RNA 3B, was detected in a TAV mutant in which one of the repeats was deleted from RNA 3. These genetic studies clearly show that both RNA species are derived from TAV RNA 3. However, in contrast to TAV RNAs 4 and 4A, which encode coat protein and 2b protein, respectively, RNAs 3B and 5 represent a novel class of subgenomic RNAs from TAV that do not function as mRNAs. Possible functional roles for such a class of viral subgenomic RNAs are discussed.

[Qualitative grading of detrusor contractility in benign prostatic hyperplasia patients]

To grade qualitatively detrusor contractility in benign prostatic hyperplasia (BPH), we studied 120 BPH patients aged from 58 to 89 years. The pressure-flow studies were performed. The passive urethral resistance relation (PURR) and Schäfer diagram were used to analyse the results. The detrusor contractility was divided into 4 classes: very weak (VW), weak (W), normal (N), and strong (ST). The types of pressure-flow were high pressure--low flow (HP-LF), high pressure--high flow (HP-HF), low pressure--low flow (LP-LF) and low pressure--high flow (LP-HF) type. The results showed that the incidence of VW, W, N and ST class was 12.5%, 26.7%, 47.5% and 13.3% respectively; the incidence of HP-LF, HP-HF and LP-LF type was 55%, 1.7% and 43.3% respectively. The weak detrusor strength could become powerful by the surgery treatment of bladder outflow obstruction (BOO) and the function training of detrusor. The detrusor strength class of a BPH patient was improved from W before surgery to N after surgery in our studies. The principles of the fluid dynamics and urodynamic and the clinical application of the qualitative grading of detrusor contractility were discussed.

[Conventional and ambulatory urodynamic study on patients with chronic prostatitis syndrome]

To study the urodynamic findings of chronic prostatitis syndrome (CPS), 58 patients with chronic prostatitis and prostatodynia were subjected to the urodynamic investigation that included conventional medium filling urodynamic (CMG) tests (urethral pressure profile, filling cystometry, voiding pressure-flow study) and ambulatory urodynamic monitoring (AM) by using Dantec Menuet and Urodec 500 AM system. 55 BPH patients and 20 normal men were taken as control groups. CPS patients had function bladder outflow obstruction (FBOO). FBOO resulted in the detrusor instable (DIS, 12.1%), detrusor-sphincter dysnergia (DSD, 100%) and detrusor dysconstractility (DDC, 6.9%), and resulted in clinical symptoms. FBOO resulted from the urethal sphincter spasm and DSD.

Differential sprouting responses in axonal fiber systems in the dentate gyrus following lesions of the perforant path in WLDs mutant mice

Axons in both peripheral nerves and central fiber pathways undergo very slow Wallerian degeneration in Wlds mutant mice. It has recently been shown that in Wlds mutant mice there is a delay in the intensification of acetylcholinesterase histochemical staining in the molecular layer of the dentate gyrus following lesions of the entorhinal cortex. Thus, it appears that delayed post-lesion reactive sprouting is associated with the delayed degeneration of cut central axons in this mutant. We have studied the time course of changes in the septohippocampal and the hippocampal commissural projections following interruption of perforant path in Wlds mutant mice and in normal (C57BL/6J) mice using the anterograde tracer, wheat germ agglutinin conjugated horseradish peroxidase. In normal mice, changes in the distribution of labeled septal and commissural axons indicative of sprouting are seen in the dentate molecular layer as early as 3 days post-lesion. The earliest survival time at which similar changes are found in Wlds mutant mice is seven days post-lesion, when an increase in the density of labeled septal axons begins in the outer molecular layer. The delay in the sprouting of commissural axons in the mutant is even longer. Changes in the distribution of labeled commissural axons in the dentate gyrus of Wlds mutant mice are first seen 12 days post-lesion. These results confirm that post-lesion reactive axonal sprouting can be delayed in the central nervous system of Wlds mutant mice. In addition, our results indicate that the extent of this delay may differ among axonal fiber systems. These findings are consistent with the notion that various central axonal systems may respond differentially to sprouting cues and are reminiscent of differences found in the regenerating response exhibited by sensory and motor axons in the Wlds mutant after peripheral nerve cuts.

Thapsigargin induces phosphorylation of the 27-kDa heat shock protein in human keratinocytes

In the human keratinocyte line HaCaT, the nonphosphorylated 27-kDa heat shock protein (HSP27) isoform A (pI 6.5) is constitutively expressed. Application of thapsigargin, which inhibits Ca2+-ATPase in the endoplasmic reticulum, results in the rapid formation of the phosphorylated HSP27 isoform B (pI 6.0) and reduction of HSP27 A without affecting the synthesis of HSP27. The thapsigargin-dependent HSP27 isoform change is similar to that induced by 43 degrees C heat shock, but different from that induced by arsenite, where the biphosphorylated isoform HSP27 C (pI 5.7) is observed. The receptor agonist bradykinin, which increases intracellular Ca2+ (Ca(i)) level, shows no effect on the distribution of HSP27 isoforms. The responses of HSP27 isoforms to thapsigargin are independent of Ca(i) concentration in HaCaT cells. These observations suggest that the thapsigargin-induced change in HSP27 isoforms is dependent on the depletion of internal Ca2+ stores rather than on the increase in Ca(i) concentration. The thapsigargin-induced change in HSP27 isoforms is reduced by the tyrosine kinase inhibitor, genistein, but not the protein kinase C inhibitor, H-7. We propose that the modulation of HSP27 phosphorylation status by Ca(i) homeostasis may be mechanistically linked to control of keratinocyte growth and differentiation and responses of keratinocytes to extracellular stresses.

Apoptosis induced by HIV-1 infection of the central nervous system

Apoptosis plays a role in AIDS pathogenesis in the immune system, but its role in HIV-1-induced neurological disease is unknown. In this study, we examine apoptosis induced by HIV-1 infection of the central nervous system (CNS) in an in vitro model and in brain tissue from AIDS patients. HIV-1 infection of primary brain cultures induced apoptosis in neurons and astrocytes in vitro as determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and propidium iodide staining and by electron microscopy. Apoptosis was not significantly induced until 1-2 wk after the time of peak virus production, suggesting induction by soluble factors rather than by direct viral infection. Apoptosis of neurons and astrocytes was also detected in brain tissue from 10/11 AIDS patients, including 5/5 patients with HIV-1 dementia and 4/5 nondemented patients. In addition, endothelial cell apoptosis was frequently detected in the brain of AIDS patients and was confirmed by electron microscopy. Most of the apoptotic cells were not localized adjacent to HIV-1-infected cells, providing further evidence for induction by soluble factors. In six non-AIDS control patients with normal brain, apoptotic cells were absent or limited to rare astrocytes. However, TUNEL-positive neurons and astrocytes were frequently detected in seven patients with Alzheimer's disease or abundant senile plaques. These studies suggest that apoptosis is a mechanism of CNS injury in AIDS which is likely to be induced by soluble factors. The apoptosis of endothelial cells in the CNS raises the possibility that some of these factors may be blood-derived.

Severe dietary magnesium deficiency does not alter levels and function of myocardial Gs alpha and Gi alpha

Magnesium ions (Mg2+) play a crucial role in the activation and synthesis of guanine nucleotide-binding proteins (G proteins). However, there is no information about the influence of in vivo magnesium deficiency on the function and levels of G proteins. This study was done to investigate whether dietary magnesium deficiency alters function and levels of the two major myocardial G proteins, Gi alpha and Gs alpha. Severe hypomagnesemia and a significant reduction of myocardial magnesium occurred in rats fed a magnesium-deficient diet for 6 wk vs. rats fed a normal-magnesium diet (control). The magnesium-deficient rats developed focal myocardial lesions but their cardiac function was not impaired. Myocardial immunodetectable Gs alpha and Gi alpha levels of magnesium-deficient rats did not differ from control (Gs alpha: 2.39 +/- 0.52 vs. 2.76 +/- 0.72 arbitrary units/microgram protein, P > 0.05; Gi alpha: 1.60 +/- 0.52 vs. 1.89 +/- 0.30 arbitrary units/microgram protein, P > 0.05). Similarly, the function of Gs alpha and Gi alpha estimated by basal and ligand-stimulated adenylyl cyclase activity was not significantly different between the two groups of animals. The results show that dietary-derived magnesium deficiency sufficient to produce severe hypomagnesemia does not produce any significant change in levels or function of myocardial G proteins.

A Raman study of the time variability for the A-to-B transition in wet-spun films of calf-thymus DNA

The time evolution of the A-to-B transition has been monitored by Raman spectroscopy and found to vary significantly for different samples. Though all samples were prepared in the identical fashion, some samples completed the transition on the time scale of several hours while other samples took days. The shortest time required for the A conformation to disappear was about 2 hours, as determined by the disappearance of the A-form Raman band at 807 cm-1. For these fastest transforming samples, the B-form Raman band at 835 cm-1 was clearly evident after about 5 hours. These data are consistent with the hypothesis that the A conformation of DNA is stabilized by intermolecular interactions.

Nitric oxide synthesis inhibition enhances bupivacaine cardiotoxicity

BACKGROUND AND OBJECTIVES

There is evidence that local anesthetic-induced seizures may be mediated by receptors for N-methyl-D-aspartate (NMDA) which activate production of nitric oxide (NO). The objective of this study was to determine the effects, if any, of inhibition of NO synthesis on the responses of the central nervous and cardiovascular systems to bupivacaine.

METHODS

Sprague-Dawley rats were assigned to two groups. The lightly anesthetized (0.5% halothane, 70% nitrous oxide) and paralyzed (doxacurium) animals were given N omega-nitro-L-arginine methyl ester (L-NAME), a NO synthase inhibitor, 2 mg/kg/min (n = 6) or saline (n = 5) intravenously for 30 minutes. Then bupivacaine was administered intravenously (2 mg/kg/min) to both groups of animals until asystole. Arterial blood samples for bupivacaine concentration analysis (by high-pressure liquid chromatography) were taken during the stabilization period and during local anesthetic infusion. Student's t-test was used to determine significant differences (P < .05) between groups.

RESULTS

Average doses of bupivacaine that produced arrhythmias and asystole were remarkably lower in L-NAME-treated than in saline-treated rats (arrhythmia, 5.1 +/- 2.0 vs 15.8 +/- 3.8 mg/kg; asystole, 15.9 +/- 3.2 vs 27.8 +/- 6.1 mg/kg; both P < .05). The doses producing seizures and isoelectric electroencephalograms and the duration of seizures did not differ significantly between the two treatment groups. However, electroencephalographic epileptiform activity was less intense (lower amplitude, shorter duration of ictal activity) in the L-NAME-treated animals. Arterial plasma concentrations of bupivacaine 5 minutes after the start of bupivacaine infusion were significantly higher in the L-NAME than in the saline group (22.3 +/- 2.9 vs 12.8 +/- 1.5 micrograms/mL, P < .05).

CONCLUSIONS

These results suggest that NO synthase inhibition by L-NAME enhances the cardiac toxicity of bupivacaine, probably by a pharmacokinetic action, and reduces its central nervous system toxicity, probably by a pharmacodynamic action.

Dietary magnesium deficiency increases Gi alpha levels in the rat heart after myocardial infarction

OBJECTIVE

Magnesium (Mg) is crucial for the function of G proteins which play important roles in mediating the inotropic effects of beta adrenergic agonists in the heart and are altered in heart failure. This study was performed to determine whether or not dietary Mg deficiency alters functional activity and levels of the two major ventricular G proteins, Gi alpha and Gs alpha in the heart after myocardial infarction (MI).

METHODS

Six week old rats were fed an Mg adequate or deficient diet for 6 weeks. At the end of week 3, MI was induced by coronary artery ligation. A sham operation was performed as control. After surgery, surviving animals were maintained on their assigned diets for another 3 weeks. Then, cardiac function was measured, plasma and tissue were collected.

RESULTS

Severe hypomagnesemia and increased plasma catecholamine level were observed in all animals fed the Mg deficient diet. A significant reduction of myocardial Mg concentration accompanied by elevated plasma and myocardial calcium concentrations was observed in MI animals with existing Mg deficiency vs. animals fed the Mg adequate diet. Cardiac function was impaired in MI rats and further reduced in MI rats with existing Mg deficiency. Gi alpha level was not altered by either Mg deficiency or MI alone, but was dramatically elevated in animals with combined Mg deficiency and MI (9.9 +/- 0.7 arbitrary unit.mg-1 protein) as compared to MI alone (5.8 +/- 0.6, P < 0.05) and Mg deficiency alone (6.1 +/- 0.8, P < 0.05). Gs alpha level did not differ between groups. GppNHp-, but not fluoride-stimulated adenylyl cyclase activity was slightly reduced in MI animals with existing Mg deficiency.

CONCLUSION

The findings suggest that dietary Mg deficiency increases the expression of Gi alpha in the heart after MI, while levels and function of Gs alpha are not compromised during dietary Mg deficiency either with or without MI.

Biological activity of human immunodeficiency virus type 1 Vif requires membrane targeting by C-terminal basic domains

Human immunodeficiency virus type 1 (HIV-1) encodes a Vif protein which is important for virus replication and infectivity. Vif is a cytoplasmic protein which exists in both membrane-associated and soluble forms. The membrane-associated form is an extrinsic membrane protein which is tightly associated with the cytoplasmic side of membranes. We have analyzed the mechanism of membrane targeting of Vif and its role in HIV-1 replication. Mutagenesis studies demonstrate that C-terminal basic domains are required for membrane association. Vif mutations which disrupt membrane association also inhibit HIV-1 replication, indicating that membrane localization of Vif is likely to be required for its biological activity in vivo. Membrane binding of Vif is almost completely abolished by trypsin treatment of membranes. These results demonstrate that membrane localization of Vif requires C-terminal basic domains and interaction with a membrane-associated protein(s). This interaction may serve to direct Vif to a specific cellular site, since immunofluorescence staining and plasma membrane fractionation studies show that Vif is localized predominantly to an internal cytoplasmic compartment rather than to the plasma membrane. The mechanism of membrane targeting of Vif is different in some respects from that of other extrinsic membrane proteins, such as Ras, Src, and MARCKS, which utilize a basic domain together with a lipid modification for membrane targeting. Membrane targeting of Vif is likely to play an important role in HIV-1 replication and thus may be a therapeutic target.

Dynamic changes in G alpha i-2 levels in rat hearts associated with impaired heart function after myocardial infarction

The objective of this study was to determine if levels and function of Gs alpha and G alpha i-2 in rat hearts change over time following acute myocardial infarction (MI), and if so, whether the changes in G proteins are associated with changes in heart function. As compared with sham-operated controls, the G alpha i-2 level of MI rats did not change at day 1, increased by 64% at day 3 (P < 0.01) and by 55% at day 9 (P < 0.05) accompanied by reduced adenylyl cyclase activity, and returned to control by day 21. By contrast, the Gs alpha level did not change at any time. Cardiac function in MI animals was markedly impaired at days 1, 3, and 9 as evidenced by substantial elevation in LVEDP and reduction in maximum rates of pressure development and relaxation, and was partially restored at day 21. Increased G alpha i-2 level in MI rats correlated significantly to severity of impaired cardiac function. The results show a three-phase dynamic pattern in G alpha i-2 level following acute MI: a lag phase, an increased expression phase associated with marked impairment of heart function, and a late phase in which the expression returns to control level accompanied by partially restored cardiac function.

Effects of nitric oxide synthesis inhibition with or without nitric oxide inhalation on responses to systemic cocaine administration in rats

The effects of N omega-nitro-L-arginine methyl ester (L-NAME) i.v. and nitric oxide (NO) inhalation on integrated systemic responses to cocaine were studied in lightly anesthetized, paralyzed, and mechanically ventilated rats. Cocaine (4 mg/kg/min i.v.) produced seizures then isoelectric electrocephalographic (isoEEG) activity as well as an initial increase in systolic blood pressure and heart rate, then progressive cardiovascular system depression culminating in asystole. Pretreatment with L-NAME (2 mg/kg/min i.v.) for 30 min significantly reduced the incidence of seizure as compared to saline treated animals (saline 7/8; L-NAME 3/8). Doses of cocaine that produced arrhythmias, isoEEG and asystole were significantly lower in the L-NAME treated animals as compared to the saline group. L-NAME did not affect peak systolic blood pressure and heart rate responses to cocaine. No inhalation (80 ppm) did not affect CNS and cardiovascular responses to cocaine in control animals but enhanced the effects of L-NAME on cocaine toxicity. The results show that pretreatment with L-NAME reduces the central nervous system stimulatory effect of cocaine (reduced seizure incidence) and enhances its depressant effect on both the central nervous system (lower does for isoEEG) and the cardiovascular system (lower dose for arrhythmias and asystole), but does not affect the cardiovascular stimulatory action of cocaine. NO inhalation does not protect against any of the systemic effects of cocaine in animals with normal or suppressed NO production.

Resuscitation from bupivacaine-induced asystole in rats: comparison of different cardioactive drugs

The objective of this study was to compare the success of resuscitation attempts with different cardioactive drugs after bupivacaine-induced asystole. Saline, amrinone (1 mg/kg), dopamine (5 micrograms/kg), norepinephrine (2 micrograms/kg), epinephrine (10 micrograms/kg), or isoproterenol (1 microgram/kg) were tested. Sixty rats assigned to six treatment groups (n = 10/group) were lightly anesthetized (0.5% halothane, 70% N2O), paralyzed (doxacurium), and given bupivacaine intravenously at 4 mg.kg-1.min-1 until asystole. Five seconds later up to three treatment drug doses were given at 30-s intervals. Then external cardiac massage was instituted as needed. Spontaneous heartbeat was restored in all animals given norepinephrine or epinephrine. It was not restored in one saline-treated, one dopamine-treated, one isoproterenol-treated, and three amrinone-treated animals. The highest (best) arbitrary scores for overall resuscitation success were achieved with norepinephrine and the lowest with amrinone (P < 0.05). The incidence of ventricular arrhythmias after resuscitation was significantly higher (P < 0.05) in epinephrine- and isoproterenol-treated animals versus other animals. Cardiac rhythm disturbance disappeared within 20 min after successful resuscitation with norepinephrine. Amrinone was no more effective than saline in treating bupivacaine-induced asystole. A drug such as norepinephrine, which has both cardiostimulator (beta 1-receptor agonist) and peripheral vasoconstrictor (alpha 1-receptor agonist) activity, may be the drug of choice for treating asystole induced by bupivacaine.

Do HLA genes play a prominent role in determining T cell receptor V alpha segment usage in humans?

Previous studies in humans have demonstrated that HLA genes can profoundly influence the TCR V beta repertoire. To similarly assess the influence of HLA genes on the TCR V alpha segment repertoire, the V alpha repertoires of 12 individuals from three unrelated families were determined by quantitative PCR. Each family contained at least one pair of HLA-identical and -nonidentical siblings. Repertoire analysis was performed on purified CD4+ and CD8+ cells by using V alpha-specific primers. We were unable to demonstrate more similar V alpha repertoires between HLA-identical siblings than between HLA-nonidentical siblings. In contrast, when a similar analysis was performed on the same individuals for the V beta repertoire, HLA-identical siblings were found to have significantly more similar repertoires than HLA-nonidentical siblings. Furthermore, both the V alpha and V beta repertoires of monozygotic twins showed striking similarity. Despite our inability to show an influence of HLA genes on the V alpha repertoire, we did observe a very strong skewing in terms of preferential expression on CD4+ or CD8+ cells of several V alpha segments, notably TCRAV1, -2, -5, -6, -7, -11, -12, and -13. These studies suggest that HLA genes play less of a role in determining V alpha segment usage than V beta. Nevertheless, the pronounced skewing of V alpha segment expression in the CD4+ or CD8+ populations suggests some role for HLA genes in determining the V alpha TCR repertoire. Furthermore, the striking similarity of V alpha repertoires of identical twins suggests a major role for non-HLA genes in determining the V alpha repertoire.

Do HLA genes play a prominent role in determining T cell receptor V alpha segment usage in humans?

Previous studies in humans have demonstrated that HLA genes can profoundly influence the TCR V beta repertoire. To similarly assess the influence of HLA genes on the TCR V alpha segment repertoire, the V alpha repertoires of 12 individuals from three unrelated families were determined by quantitative PCR. Each family contained at least one pair of HLA-identical and -nonidentical siblings. Repertoire analysis was performed on purified CD4+ and CD8+ cells by using V alpha-specific primers. We were unable to demonstrate more similar V alpha repertoires between HLA-identical siblings than between HLA-nonidentical siblings. In contrast, when a similar analysis was performed on the same individuals for the V beta repertoire, HLA-identical siblings were found to have significantly more similar repertoires than HLA-nonidentical siblings. Furthermore, both the V alpha and V beta repertoires of monozygotic twins showed striking similarity. Despite our inability to show an influence of HLA genes on the V alpha repertoire, we did observe a very strong skewing in terms of preferential expression on CD4+ or CD8+ cells of several V alpha segments, notably TCRAV1, -2, -5, -6, -7, -11, -12, and -13. These studies suggest that HLA genes play less of a role in determining V alpha segment usage than V beta. Nevertheless, the pronounced skewing of V alpha segment expression in the CD4+ or CD8+ populations suggests some role for HLA genes in determining the V alpha TCR repertoire. Furthermore, the striking similarity of V alpha repertoires of identical twins suggests a major role for non-HLA genes in determining the V alpha repertoire.

Selenium from beef is highly bioavailable as assessed by liver glutathione peroxidase (EC 1.11.1.9) activity and tissue selenium

The bioavailability of Se from ground beef has been previously found in this laboratory to be greater than that of selenite or selenate when fed to female Fischer 344 rats. In the present study we examined the bioavailability of Se from various commercial portions of beef, the liver, striploin, round, shoulder and brisket. All beef was cooked, freeze-dried, finely powdered and mixed with the other dietary ingredients. The experimental diets were fed to the weanling Fischer 344 rats which had been subjected to dietary depletion of Se for 6 weeks. The bioavailability of Se from the beef diets was compared with that of Se as selenite or L-selenomethionine (SeMet) added to torula-yeast diets. Each experimental diet contained 0.10 mg Se/kg. After 8 weeks of dietary Se repletion, relative activity of liver glutathione peroxidase (EC 1.11.1.9; GSHPx) from the different dietary groups compared with that of control animals (100%) was (%): selenite 91, SeMet 122 (P < 0.05), liver 108, striploin 105, round 106, shoulder 106, brisket 103. Se recovery for liver GSHPx was generally highest from SeMet > beef muscle = beef liver > selenite. Muscle tissue deposition of Se was highest from SeMet > beef muscle > selenite = beef liver. In addition, the faecal excretion of Se was lowest from the SeMet dietary group and highest from the selenite dietary group. The experimental results suggest that all cuts of beef appear to be highly bioavailable sources of dietary Se when compared with selenite or L-SeMet.

Bioavailability of selenium from raw and cooked ground beef assessed in selenium-deficient Fischer rats

OBJECTIVE

The literature on the bioavailability of selenium (Se) from meats, especially beef, is meager, and that which existed when this research began suggested that Se was not highly bioavailable. In addition, much of the analytical values for Se in beef predated the Food and Drug Administration's 1973 approval of Se as an additive to feeds and mineral premixes of livestock.

DESIGN

One hundred and thirty-six weanling female Fischer 344 rats were divided into two dietary groups: the selenium deficient group in which animals were fed a torula yeast (TY) basal diet which contained 0.008 mg/kg Se and the control group in which animals were fed the TY diet to which was added 0.10 mg/kg Se as sodium selenite.

RESULTS

After 6 weeks of dietary treatment liver glutathione peroxidase (GSHPx) activity had fallen in the Se-deficient rats to 2.4% of that of control rats. At this time (week 6) rats from the Se-deficient TY diet were refed diets containing 0.10 mg/kg Se as selenite, selenate, raw or cooked ground beef that had been freeze-dried. During the Se-repletion period rats were sacrificed at weeks 1, 3, 5 and 8. Liver GSHPx activity and total Se levels in liver and muscle tissue were the criteria of Se bioavailability. After 8 weeks of Se resupplementation the recovery of liver GSHPx activity compared to the control animals (set at 100%) were selenite (98%, p > 0.05), selenate (117%, p < 0.05), raw beef (127%, p < 0.05) and cooked ground beef (139%, p < 0.05). Total Se in both liver and muscle tissue reflected the liver GSHPx activity with the total Se concentration in tissues being highest for cooked beef.

CONCLUSION

The data suggest that bioavailability of Se from ground beef is greater than that from either selenite or selenate.

Aluminum interaction with phosphoinositide-associated signal transduction

Concerning molecular and cellular mechanisms of aluminum toxicity, recent studies support the hypothesis that interactions of aluminum ions with elements of signal transduction pathways are apparently primary events in cells. In the case of the phosphoinositide-associated signalling pathway of neuroblastoma cells, guanine nucleotide-binding proteins (G proteins) and a phosphatidylinositol-4,5-diphosphate (PIP2)-specific phospholipase C are probable interaction sites for inhibitory actions of aluminum ions. Following interiorization of aluminum by the cell, metal interactions decrease the accumulation of inositol phosphates, especially that of inositol-1,4,5-triphosphate (IP3), concomitant with derangements of intracellular Ca2+ homeostasis. In the presence of high concentrations of Ca2+, formation of IP3 is also diminished in aluminum-pretreated cells, presumably involving a process not requiring Mg(2+)-dependent G proteins. At higher aluminum doses, metal-induced changes in the lipid milieu of the membrane-bound phospholipase may play a role. These types of primary interactions of aluminum ions with elements of cellular communication channels are probably crucial in the manifestation of the multifacetted aluminum toxicity syndrome. If present as a phosphate-like fluoro-aluminate, a stimulatory role of aluminum ions is displayed in G protein-coupled transmembrane signalling.