A biomechanical analysis of unilateral hooked-sulcated external fixator on osteomined tibia

Four tibiae removed from 30-40 years males, who died of accidents in less than 12 hours, were osteomized at medium part. Then these tibiae were fixed by an unilateral hooked-sulcated external fixator (UHSEF), and the bone-fixator system was used as a model of external fixation of tibial fracture. The axial compression, distraction, torsion, antero-posterior and lateral bending rigidity and the strain of the pins were determined in this system. Based on the results, we found that compared with the configuration of four paralleled pins, the rigidity of the fan-like configuration didn't decrease significantly if the angle between lateral and medium pins was less than 45 degrees. But the reverse was true when the frame separation increased from 5 to 8 cm. What' more, the pin strain decreased if the rigidity of the system was improved. These data provided a theoretical basis of biomechanics for the improvement of UHSEF.

Castration decreases extracellular, but increases intracellular, dopamine in medial preoptic area of male rats

Dopamine (DA) is released in the medial preoptic area (MPOA) of male rats in the presence of a female, and it facilities male sexual behavior. Castration blocks the DA response to a female and the male's ability to copulate. The present experiments examined the effects of castration on (1) basal levels of extracellular DA in the MPOA, using the no net flux microdialysis technique, (2) the response of extracellular DA to amphetamine, and (3) tissue levels of DA. Castrated rats had lower basal levels of extracellular DA in the MPOA, compared with gonadally intact rats; in vivo recovery, a measure of uptake, was not different. This suggests that castration decreases DA release in basal conditions, as well as in response to a female. However, systemic amphetamine injections, which induce DA release, resulted in greater DA release in castrates. Finally, tissue levels of DA were higher in the MPOA, the caudate-putamen and the bed nucleus of stria terminalis of castrates. These data suggest that DA synthesis and storage in the MPOA are normal, or even enhanced, in castrates, and uptake is not altered. The deficit in extracellular levels appears to be related to release, perhaps due to decreased nitric oxide.

Integration of visual and tactile modalities

Experiments have been carried out in which subjects were required to discriminate time-varying visual and tactile stimuli presented simultaneously via a 2D array of light-emitting diodes and a vibrator on the fingertip. Contrary to expectations, no problems in parallel visual and tactile perception were apparent. Similar results were obtained in a second experiment in which subjects were require to lipread from a video image and simultaneously identify speech-derived tactile stimuli. The generally poor performance of tactile aids to lipreading has been attributed to problems of parallel perception, but such problems are clearly not present in all circumstances.

The bacterial inhibitory ability and in vivo drug release pattern of a new drug delivery system: ciprofloxacine/tricalcium phosphate delivery capsule

The bacterial inhibitory ability of a new drug delivery system (DDS): Ciprofloxacine/tricalcium phosphate delivery capsule (CTDC), its in vivo drug release pattern, and the influence of ultrasonic irradiation on its drug release were investigated. It was found that CTDC had a strong and sustained inhibitory ability to some common pathogens of bone and joint infections, such as staphylococcus aureus, escherichia coli and pseudomonas aeruginosa. In vivo drug-release study in animals demonstrated a high concentration of ciprofloxacine in the bone tissue surrounding CTDC which was placed in the greater trochanter of the rabbit and continued to release ciprofloxacine for at least 5 weeks and the blood level of ciprofloxacine was low. In vivo study also showed ultrasonic irradiation could increase the amount of ciprofloxacine released from CTDC, which may be an economical, effecient and safe new method to achieve the control of drug release from DDS.

Asymmetric synthesis of oxazolidine nucleosides and related chemistry

Asymmetric synthesis of N-substituted oxazolidinyl nucleosides has been accomplished from L-isoserine, trans- and cis-Oxazolidine intermediates (4 and 5) were stereoselectively constructed from N-protected L-isoserine with a menthoxycarbonyl group by the condensation with benzoyloxy acetaldehyde dimethyl acetal in a ratio of 3.9 to 1 in favor of trans-isomer 4. The major isomer 4 was converted to enantiomerically pure beta- and alpha-N-L-menthoxycarbonyl oxazolidinyl thymine nucleosides 11 and 12 in 6 steps.

Key peptide processing enzymes are expressed by a variant form of small-cell carcinoma of the lung

Small-cell carcinoma of the lung (SCCL) is a neuroendocrine tumor characterized by having the capacity to produce and secrete a number of small neuropeptides. These peptides serve the tumor as autocrine growth factors. SCCL is known to undergo a process of dedifferentiation to a variant (drug-resistant) form, and this process is associated with loss of marker enzymes such as neuron-specific enolase (NSE) and dopa decarboxylase (DDC). The current study was designed to discover if variant SCCL, represented by cell line NCI H82, retains some capacity to generate active neuropeptides (like vasopressin) from their precursors by continuing to express the three key classes of enzymes necessary for such conversions, namely prohormone convertases (PCs), carboxypeptidases (CPs), and peptidylglycine a-amidating monooxygenase (PAM). RT-PCR for mRNAs representing PC1, PC2, CPE, and PAM was performed on total RNA extracted from NCI H82. The primers selected for PCR and partial sequencing were synthetic 20, 21, 22, and 24 oligomers designed to yield products of 533, 880, 405, and 560 base pairs (bp) for PC1, PC2, CPE, and PAM, respectively. For the conditions used, we were able to demonstrate products for all four enzymes. Each of the four products generated were of the expected size. Cloning and sequencing of these products revealed that each had a structure identical to that published for the human form of the respective enzyme. Western analysis with antibodies against PC1, PC2, CPE, and PAM, provided evidence that mRNAs for the four enzymes are translated into proteins that could represent functional forms. Our findings therefore demonstrate that key enzymes involved in the generation of active neuropeptides, unlike the marker enzymes NSE and DDC, continue to be expressed by variant SCCL.

Biodegradation of tricalcium phosphate ceramics by osteoclasts

Biodegradation of tricalcium phosphate (TCP) ceramics was observed through mixed culture of osteoclasts and TCP discs in vitro in this study. Osteoclasts were isolated from newborn SD rat's marrow of long bone and cultured on TCP discs. The culture terminated at the 48th h and 96th h respectively. Under an inverted microscope, the osteoclasts imparted round or oval body with multinuclear and many thin processes. These cells were positively stained for tartrate-resistance acid phosphatase (TRAP). Scanning electron microscope showed that many resorption lacunae on TCP disc surface and their diameters were smaller than 20 microns. Osteoclasts were located in the lacunae. At the 96th h, the resorption lacunae become larger and osteoclasts showed degeneration. It is suggested that osteoclasts possess ability to re-absorb TCP ceramics under in vitro culturing condition.

[Effect of captopril on platelet cytosolic [Ca2+]i and plasma TXA2/PGI2 in renovascular hypertensive rats]

AIM

To study the effect of captopril (Cap) on platelet cytosolic free calcium concentration ([Ca2+]i), platelet aggregation (PAg), and plasma TXA2/PGI2 ratio in the renovascular hypertensive rats.

METHODS

Blood pressure was measured once a week by tail-cuff microphonic manometer. Platelet [Ca2+]i was measured by Fura 2-AM. Plasma angiotensin II (Ang), thromboxane A2 (TXA2), and prostacycline (PGI2) were measured by radioimmunoassay.

RESULTS

Platelet [Ca2+]i and PAg increased (P < 0.01), while plasma Ang and TXA2/PGI2 ratio elevated (P < 0.05) in the renovascular hypertensive rats; platelet [Ca2+]i and plasma TXA2/PGI2 ratio reduced markedly after i.g. Cap 100 mg.kg-1.d-1 compared with saline for 2 wk.

CONCLUSION

The altered TXA2/PGI2 after Cap treatment contributed to the improvement of the platelet [Ca2+]i and PAg.

Studies on the ossification of compound transplantation of porous TCP ceramics and bone marrow

Following the culture of human red marrow with porous TCP ceramics in vitro, a large amount culturing marrow cells adhered well to the surface and inner wall of TCP ceramics and spread well over the dish bottom 4 weeks after cultivation. After the compound transplantation of porous TCP ceramics with red marrow into quadriceps femoris muscle of rabbits, a huge amount of new bone and marrow formed in these sites on and in the ceramics 4 weeks after transplantation. These results showed an excellent biocompatibility between TCP ceramics and marrow and an excellent osteogenic effect in the compound transplantation. The mechanism of ossification and clinical significance about the compound transplantation were discussed.

Testosterone, preoptic dopamine, and copulation in male rats

Steroid hormones prime neural circuits for sexual behavior, in part by regulating enzymes, receptors, or other proteins affecting neurotransmitter function. Dopamine facilitates male sexual behavior in numerous species and is released before and/or during copulation in three integrative neural systems. The nigrostriatal system enhances readiness to respond; the mesolimbic system promotes many appetitive behaviors; the medial preoptic area (MPOA) contributes to sexual motivation, genital reflexes, and copulation. We have reported a consistent relationship between precopulatory dopamine release in the MPOA, when an estrous female was behind a perforated barrier, and the ability to copulate after the barrier was removed. Recent, but not concurrent, testosterone was necessary for the precopulatory dopamine response and copulation. The deficit in MPOA dopamine release in castrates was observed in basal conditions as well as the sexual context. However, dopamine in tissue punches from castrates was higher than in intact males. Because tissue levels represent primarily stored neurotransmitter, dopamine appeared to have been synthesized normally, but was not being released. Amphetamine induced greater dopamine release in castrates, again suggesting excessive dopamine storage. The decreased release may result from decreased activity of nitric oxide synthase in the MPOA of castrates. A marker for this enzyme showed lower activity in castrates than in intact males. Finally, blocking nitric oxide synthase in intact males blocked the copulation-induced release of dopamine in the MPOA. Therefore, one means by which testosterone may promote copulation is by upregulating nitric oxide synthesis in the MPOA, which in turn enhances dopamine release.

[Effect of CRF, AVP and NE on cAMP in cultured rat anterior pituitary cells during hypoxia]

In the study, the effect CRF (corticotropin-releasing factor), AVP (argipressin) and NE (norepinephrine) on cAMP formation in cultured rat anterior pituitary cells in vitro was examined and the effect of cAMP formation between normoxia and hypoxia (8%O2) was compared. CRF stimulated the formation of cAMP levels which was correlated with the concentration of CRF in medium. The cAMP levels in medium increased. The intracellular cAMP in cultured anterior pituitary cells was not changed by AVP. The concentration of intracellular cAMP was decreased by NE, but the content of extracellular cAMP was no changed. Hypoxia decreased the stimulating effects of CRF on the cAMP formation in cultured anterior pituitary cells.

Ig Sgamma3 DNA-specifc double strand breaks are induced in mitogen-activated B cells and are implicated in switch recombination

The looping-out and deletion model of switch recombination suggests that double strand breaks (DSBs) may occur in switch regions and participate in the recombination transaction. A DSB assay based on the ligation-mediated PCR method has been devised for the Sgamma3 region. Mitogen-inducible DSBs have been detected in Sgamma3 DNA of normal splenic B cells but not in splenic T cells or thymocytes. The breaks are restricted to the Sgamma3 region and are sequence specific. Examination of the sequence surrounding the DSBs has led to the derivation of a consensus sequence for DSB formation. Induction of Sgamma3-specific DSBs is correlated with the onset of switch recombination. The DSBs flank clusters of Sgamma3 recombination breakpoints, suggesting that processing of the broken ends may occur during the recombination reaction.

[Atypical manigioma]

Most meningiomas have typical clinical and CT features. But some meningiomas which have an atypical clinical and CT findings can lead to a wrong diagnosis. The authors have reviewed 123 hospitalized patients with meningiomas which had been pathologically diagnosed. Nine of them had atypical meningiomas according to their histories, symptoms, signs and CT findings. All of these patients were mis diagnosed as having gliomas or metastatic tumors. The authors analyed these cases carefully and find the clues that may help to do an accurate preoperative diagnosis.

Ig Sgamma3 DNA-specifc double strand breaks are induced in mitogen-activated B cells and are implicated in switch recombination

The looping-out and deletion model of switch recombination suggests that double strand breaks (DSBs) may occur in switch regions and participate in the recombination transaction. A DSB assay based on the ligation-mediated PCR method has been devised for the Sgamma3 region. Mitogen-inducible DSBs have been detected in Sgamma3 DNA of normal splenic B cells but not in splenic T cells or thymocytes. The breaks are restricted to the Sgamma3 region and are sequence specific. Examination of the sequence surrounding the DSBs has led to the derivation of a consensus sequence for DSB formation. Induction of Sgamma3-specific DSBs is correlated with the onset of switch recombination. The DSBs flank clusters of Sgamma3 recombination breakpoints, suggesting that processing of the broken ends may occur during the recombination reaction.

Protein kinase C alpha-mediated chronic signal transduction for immunosenescence

In CD2/protein kinase C alpha (PKC alpha)-overexpressing human CD2/rabbit PKC alpha transgenic mice, an aging-dependent increase in PKC alpha expression and a decrease in proliferative responsiveness of splenic T cells were promoted. We found that an aging-associated accumulation of CD44(high) CD45RB(low) memory CD4+ T cells in exchange for CD44(low) CD45RB(high) naive CD4+ T cells was promoted in transgenic mice. A disequilibrium between Ag-dependent generation and subsequent elimination of memory T cells in these mice was shown to underlie this phenomenon. When stimulated with Ag, the PKC alpha transgenic mice responded poorly regarding Ab production and produced cytokines biased for high IFN-gamma/IL-12 and low IL-4/IL-10 levels. These results prove, for the first time, a causal role for chronic signal transduction through PKC alpha in aging-associated immunodysfunction and provide the first animal model for genetically promoted immunosenescence.

[Inherited defect of platelet nitric oxide synthase activity in essential hypertension]

The collagen-provocated platelet nitric oxide synthase (NOS) activity by the method of 3H-labelled L-arginine was compared between 19 essential hypertensives (EH) and 21 controls, and between 13 adolescents with their both parent hypertensives (FH+) and 12 adolescents without genetic hypertensive predisposition (FH-) as well. Results showed that the platelet NOS activity was lower significantly in EH group (4.76 +/- 2.01 vs 8.09 +/- 2.36 pmol.g-1.min-1, P < 0.001) and in FH+ group (3.64 +/- 2.07 vs 5.51 +/- 2.13 pmol.g-1.min-1, P < 0.05) comparing with their control groups respectively. It suggests that the inherited defect of some anti-hypertensive mechanisms like NO/NOS system may be implicated in the development of EH, which can be taken as a new "genetic marker" for detecting of specific clinic subtype. An useful data was thus presented of value in screening referred genes, for early prevention and rational remedy in essential hypertension.

Protein kinase C alpha-mediated chronic signal transduction for immunosenescence

In CD2/protein kinase C alpha (PKC alpha)-overexpressing human CD2/rabbit PKC alpha transgenic mice, an aging-dependent increase in PKC alpha expression and a decrease in proliferative responsiveness of splenic T cells were promoted. We found that an aging-associated accumulation of CD44(high) CD45RB(low) memory CD4+ T cells in exchange for CD44(low) CD45RB(high) naive CD4+ T cells was promoted in transgenic mice. A disequilibrium between Ag-dependent generation and subsequent elimination of memory T cells in these mice was shown to underlie this phenomenon. When stimulated with Ag, the PKC alpha transgenic mice responded poorly regarding Ab production and produced cytokines biased for high IFN-gamma/IL-12 and low IL-4/IL-10 levels. These results prove, for the first time, a causal role for chronic signal transduction through PKC alpha in aging-associated immunodysfunction and provide the first animal model for genetically promoted immunosenescence.

Percutaneous reduction and stabilization of complex tibial plateau fractures

Mechanical traction and percutaneous reduction by leverage and fixation by a bilateral groove external fixator were performed on 23 patients with complex tibial plateau fractures involving a depressed and split fragments. The fixator is composed of two long groove frames, three to five nuts, hooked bolts and Steinmanns pins. All fractures united in good position in three months with no incision (only pinpricks), little operative trauma and no significant complications but pintract infection, and the flexion-extension range of knee movement was excellent in all patients, so that this technique is particularly advisable for complex tibial plateau fractures.

Synthesis of L-ribofuranosyl C-nucleosides

C-Nucleosides, 4-amino-8-(beta-L-ribofuranosyl)pyrazolo[1, 5-a]-1,3,5-triazine (12) and 4-amino-7-(beta-L-ribofuranosyl)-5H-pyrrolo[3,2-d]pyrimidine (L-9-deazaadenosine, 22), were synthesized from the key intermediate, 3-dimethylamino-2-(2,3-O-isopropylidene-5-O-trityl-L-ribofuranosyl) acrylonitrile (8), which was prepared from L-xylose in 11 steps.

Type 1 HERV-K genome is spliced into subgenomic transcripts in the human breast tumor cell line T47D

Two types of HERV-K genomes exist which differ in the absence (type 1) or the presence (type 2) of a sequence of 292 nucleotides between the putative pol and env genes. Previously published results from teratocarcinoma cell studies had firmly concluded that the type 1 HERV-K genome was defective in splicing and that only the nondeleted type 2 HERV-K genome containing the 292-nucleotide sequence was capable of being spliced. We now show that in the T47D human breast tumor cell line it is the type 1 HERV-K genome, and not the type 2, which is spliced to subgenomic transcripts.

[Effect of hypoxia on spleen mono nuclear cell DNA content and proliferation of neonatal rats]

Effects of hypoxia on the immune function of neonatal rats at the age of 14 days as well as on the levels of ACh, catecholamine in spleen were studied. After the animals were exposed to hypoxia at 5 km simulated altitude in hypobaric chamber for 5 days, there was 43.4% decrease in DNA content in spleen mono nuclear cell and a 13.2% decrease in mono nuclear cell proliferation. Similar suppression of these two parameters of immune function in exposure to 7 km for 24 h was also noted, which decreased by 39% and 19.8% respectively. The suppressive effect of 7 km for 24 h hypoxia on DNA content was partly blocked when rats were pretreated with DSP-4 intracerebroventricularly one day before hypoxia. The levels of catecholamine in spleen increased, while the levels of ACh decreased after 7 km exposure for 24 h. These observations indicate that hypoxia may suppress cellular function of neonatal rats and its action may be mediated by activation of sympathetic nervous system and inhibition of parasymphathetic one.

Analysis of immunoglobulin Sgamma3 recombination breakpoints by PCR: implications for the mechanism of isotype switching

The molecular mechanism of immunoglobulin switch recombination is poorly understood. Switch recombination occurs between pairs of switch regions located upstream of the constant heavy chain genes. Previously we showed that switch recombination breakpoints cluster to a defined subregion in the Sgamma3, Sgamma1 and Sgamma2b tandem repeats. We have developed a strategy for direct amplification of Smu/Sgamma3 composite fragments as well as Smu and Sgamma3 regions by PCR. This assay has been used to analyze the organization of Smu, Sgamma3 and a series of Smu/Sgamma3 recombination breakpoints from hybridomas and normal mitogen-activated splenic B cells. DNA sequence analysis of the switch fragments showed direct joining of Smu and Sgamma3 without deletions or duplications. Mutations were found in two switch junctions on both sides of the crossover point, suggesting that template switching is the most likely model for the mechanism of switch recombination. Statistical analysis of the positions of the recombination breakpoints in the Sgamma3 tandem repeat indicates the presence of two sub-clusters, suggesting non-random usage of DNA substrate in the recombination reaction.