Embryonic platelet activating factor production in the rabbit increases during the preimplantation phase

Objective This study measured platelet activating factor (PAF) production by rabbit embryos in vitro and ascertained if there is increased PAF production associated with advancing embryonic development.Study Design Two-cell rabbit embryos were recovered from superovulated New Zealand White does and cultured in vitro for 96 hr. Every 24 hr embryos were scored for developmental stage and PAF activity from the corresponding culture medium was measured by platelet aggregation and organic phosphate analyses.Results PAF was detected in culture medium at all stages from two cells to blastocysts and rose significantly (P <0.001) at each 24-hr interval, reaching maximal levels at the expanded blastocyst stage. Conclusion Maximal PAF production by expanded blastocysts may be an embryonic paracrine signal that facilitates implantation.Presented at the 48th Annual Meeting of The American Fertility Society, New Orleans, Louisiana, October 31–November 5, 1992.     

低功率半导体激光照射对神经功能恢复的影响

目的　探讨低功率半导体激光对家兔神经功能恢复的影响。方法　用 3 6只体重 2 5kg左右的家兔随机分为 3、6、9和 1 2周 4个观察期组 ,每个观察期组随机分为半导体激光照射组 (各用家兔 5只 )和对照组 (各用家兔 4只 )。麻醉后 ,均切断左侧腓总神经 ,用 9/0尼龙单丝对端吻合神经外膜。各照射组在术后 1d开始照射家兔L5 ,6脊髓节段 ,照射激光输出功率为 2mW ,每天照射 5min,连续照射 7d。对照组不照射 ,均按期观察。结果　术后 3周 ,可在照射组看到细小而稀少的再生轴突 ,对照组直到术后 6周才看到 (P <0 0 1 )。照射组的腓总神经潜伏速率均优于对照组 (P <0 0 1 ) ,动作电位波幅照射组也优于对照组。展趾功能到术后 1 2周 ,照射组与侧健相同 ,对照组才恢复到照射组 6周的水平。结论　低功率的半导体激光可促进脊髓运动神经细胞功能 ,加速轴突再生。     

Effects of Zinc on Burns Healing and Correlation Between Serum Zinc and Serum Protein and Alkaline Phosphatase in Burned Rabbits

We report herein effects of varying dietary zinc contents on burns healing andcorrelation between serum zinc and serum alkaline phosphatase (AKP) activity and serumprotein in 15% total body surface area (TBSA) of Ⅲ°burned Lop rabbits.Serum zincconcentration in the rabbits given a low zinc diet for 2 weeks and those with burnsdecreased significantly,and further decreased and failed to return to normal in the rabbitwith a low zinc diet and burns.On the contrary,serum zinc was recovered rapidly tonormal in the groups fed an adequate zinc diet.Similar changes were found in serum AKPactivity.Postburn total serum protein and albumin contents were markedly decreased anddid not return to normal on d 15.Burns healing in the high zinc group was over 10 dfaster than that in the low zinc group.Serum zinc was found to be well correlated withserum AKP activity and serum protein.These results strongly suggest that zinc might be afactor benefiting burns healing.We conclude that serum AKP activity could be used as adiagnostic criterion of postburn hypozincemia as well as a valid index in the assessment ofthe effectiveness of supplemental zinc.     

静脉注射印防己毒素对丘脑束旁核伤害性放电的影响

细胞外玻璃微电极记录丘脑束旁核神经元的伤害性放电。静脉注射惊厥下剂量印防己毒素0.4～0.8mg/kg,分别对注射前后的束旁核神经元伤害性放电的频率,脉冲个数、放电时程进行分析,结果表明:γ-氨基丁酸拮抗剂印防己毒素对束旁核神经元伤害性放电具有明显抑制作用。共观察了13个单位,其中有9个单位静脉注射印防己毒素后反应为放电时程缩短,脉冲总数减少,放电频率降低。3个单位出现易化效应,1个单位药物注射后放电活动无明显变化。     

小诺霉素的药物动力学研究

报告微生物法测定血清中小诺霉素浓度,并用于家兔静脉和肌内给药及细菌性感染患者肌内给药的药物动力学研究。家兔静脉给药5mg/kg,药物动力学方程为C=~-27.36e~(-13.65(?))+22.07e~(-0.505t);家兔肌内给药5mg/kg,药物动力学方程为c=15.10(e~(-0.4(?)7)-e~(-5.143t)。吸收迅速完全,30min 可达高峰。在10例感染性疾病患者中,一次肌内给药120mg 小诺霉素,吸收迅速,平均达峰时间为0.76h,平均峰浓度9.61ug/ml,平均消除半衰期为2.63h。个体差异较大。     

兔实验性动脉粥样硬化血浆脂蛋白脂酶和肝脂酶活性的变化

初步建立了兔肝素化血浆脂蛋白脂酶(LPL)和肝脂酶(HL)活性的测定方法,两种脂酶活性以水解三油酸甘油酯(TG)生成游离脂肪酸(FFA)的含量表示。测得雄性日本大耳白兔肝素化后15min血浆LPL、HL活性最大,批内差异分别为4.96%、3.26%;正常兔LPL、HL分别为12.15±4.07μmol·L~(-1)FFA/h·ml、17.11±6.80μmol·L~(-1)FFA/h·ml;实验兔喂饲胆固醇12wk形成动脉粥样硬化(AS)时LPL、HL活性分别为7.94±3.36μmol·L~(-1)FFA/h·ml、4.54±1.52μmol·L~(-1)FFA/h·ml,两者均较正常兔明显降低(P<0.005)。提示:在高胆固醇负荷时,LPL、NL活性降低可能促进了AS的形成。     

Growth in Rabbits during Alternate-Day Cortisone Injections: Near Normal Growth on Days without Cortisone

ABSTRACT. Longitudinal bone growth in rabbits during treatment with hydrocortisone was measured by means of Roentgen Stereophotogrammetric Analysis, RSA. This method allows accurate measurement of the distance between metallic markers inserted into long bones. Hydrocortisone was given in i.m. injections as single doses and as repeated doses, daily or every other day. Single injections of hydrocortisone resulted in three types of growth effect, depending on dosage. Low dosage (less than 4 mg/kg b.w.) produced no blunting of growth. Intermediate dosage (4–32 mg/kg b.w.) retarded growth during the first but not the second day after the injection. The effect of high dosage (64–128 mg/kg b.w.) lasted for two days. During daily treatment (4 and 16 mg/kg b.w.), growth decreased to a constant level. During alternate-day steroid injections with a double dose every other day, growth almost normalized during the steroid-free days. Average growth was significantly greater during alternate-day injections than during daily injections. It is concluded that alternate-day treatment has no unfavorable effect on growth so long as the interval between injections exceeds the duration of the growth effect of each single dose.     

Myocardial Pharmacokinetics of Lithium in Vitro

Abstract The myocardial pharmacokinetics of ionised lithium were investigated in isolated, intact rabbit hearts, which were retrogradely perfused with a modified Krebs-Henseleit solution containing lithium in a concentration of 5 mM. The rate of myocardial accumulation of lithium as a function of time was indirectly followed at constant coronary flow by means of determinations of the lithium content of fractional samples of the coronary output of perfusate collected during the lithium perfusion period. The disposition rate of lithium from the myocardium was similarly determined with respect to the time lapse after the perfusion had been switched over to a lithium-free liquid. The accumulation and disposition processes were found to fit bi-exponential functions, as an expression of the myocardium behaving as a two-compartment system obeying apparently first order, linear kinetics with respect to ionised lithium. A pronounced decrease of the uncomposite elimination rate constants k₁₀ and especially k₂₁ was observed after continuous perfusion with 5 mM lithium perfusion liquid for about 30 min. During this perfusion period at steady state, an absolute increase of myocardial lithium accumulation obviously took place. A possible correlation of these findings to the cardiac effects of lithium is discussed.     

IRON AND THE REGULATION OF ERYTHROPOIESIS

Recent work is reviewed suggesting that iron deficiency in suckling rabbits is contributory to early postnatal anemia. The evidence against a similar factor operating in humans is discussed.     

Cingulate cortical and anterior thalamic neuronal correlates of the overtraining reversal effect in rabbits

Multiple-unit activity of the cingulate cortex and the anteroventral (AV) nucleus of the thalamus in rabbits was recorded during reversal training, following differential conditioning of a locomotory (wheel rotation) avoidance response. The CS+ and CS? were pure tones (1 or 8 kHz) and the UCS was a footshock delivered through the grid floor of the wheel. One group of the rabbits received original training to a criterion followed immediately by reversal training. A second group received training to criterion followed by additional training sessions (overtraining), prior to reversal training. The results indicated that the overtraining reversal effect (ORE) occurred. That is, the overtrained subjects acquired the reverse discrimination in significantly fewer sessions than the non-overtrained subjects. The overall (non-discriminative) neuronal reactivity in all cingulate cortical laminae was reduced by overtraining, whereas the overall reactivity of the AV thalamus was enhanced. In addition, the non-overtrained subjects manifested a discriminative neuronal response appropriate to the original task (i.e. a greater response to the CS? than to the CS+ for reversal training), throughout the precriterial sessions of reversal training. This persistent ‘original habit effect’ occurred only at brief latencies (20–30 msec) after CS onset, and only in the deep cortical laminae (V–VI). The neuronal activity of the superficial laminae (I–IV) in non-overtrained subjects underwent a transition, in parallel with the behavior, from a discriminative response appropriate to the original task to one appropriate to the reversal task. No significant training-related changes were seen at any cortical depth in the overtrained subjects. Presentation of non-contingent footshocks during two sessions of reversal training following criterion re-enhanced the overall reactivity and the brief-latency discriminative neuronal response appropriate to the original task, which had undergone decline during reversal training, in the deep cortical laminae of the non-overtrained subjects. The enhanced overall reactivity and the discriminative activity in the superficial laminae of non-overtrained subjects had not declined during reversal training and were not altered by the non-contingent footshocks. The implications of these data are discussed in regard to the neural causation of the ORE.