Mass and in situ molar activity of tyrosine hydroxylase in the median eminence. Effect of thyroidectomy and thyroid hormone replacement

The effects of thyroidectomy and thyroid hormone replacement on the mass and in situ molar activity of tyrosine hydroxylase (TH) in the median eminence (ME) and superior cervical ganglia (SCG) of male rats were investigated. The tissue specificity of these effects were evaluated by comparing the ME with the superior cervical ganglion (SCG). All animals were thyroparathyroidectomized (Tx) or sham Tx. Tx rats were treated daily for 3 weeks with 0.15 M NaCl (solvent vehicle) or L-thyroxine (T4). Two doses of T4, 10 and 100 micrograms/day/kg BW, were used. Sham Tx rats were treated with 0.15 M NaCl. All animals were studied on the day following the last treatment. The mass of TH was determined using an immunoblot assay, and the in situ activity of TH was calculated from the rate of intracellular accumulation of L-dihydroxyphenylalanine (DOPA) after administration of an inhibitor of DOPA decarboxylase activity. In the ME, thyro-parathyroidectomy resulted in a 40% increase in the mass and a 100% increase in the in situ molar activity of TH over that of sham Tx rats. Compared to Tx animals given 0.15 M NaCl, Tx rats treated with a low dose of T4 (10 micrograms/day/kg BW) had a reduced quantity of TH in the ME, but the molar activity of the enzyme was increased. Treatment of Tx rats with a high dose of T4 (100 micrograms/day/kg BW) restored TH mass but not the in situ activity of TH in the ME to the level seen in sham Tx rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influenza B virus reinfection

Four outbreaks of influenza B infection occurred in Houston, Texas in the years 1976-1984. In the Houston Family Study, age-related infection and illness rates in the recent two epidemics resembled those reported previously. A total of 118 persons, including 35 children followed from birth, were followed longitudinally through this entire period and 331 persons were studied through at least two outbreaks. Fifty-nine (88%) of 67 children studied for four outbreaks were infected and 25% had a second infection; about half of the adults had one infection but only one of 51 was reinfected. Infection rates were proportionally lower for those followed through 2-3 outbreaks. Those with documented infection were protected decreasingly over time against reinfection and associated illness in subsequent epidemics. Such protection decreased in efficacy from 65% after 2-3 years, to 46% after 4-5 years, and to no protection after seven years.     

Hemorrhagic and nonhemorrhagic brain lesions: evaluation with 0.35-T fast MR imaging

Two fast magnetic resonance (MR) imaging techniques, advanced Fourier and partial-flip imaging, were used at 0.35 T to examine 21 patients with suspected intracranial lesions; the results were quantitatively compared with a conventional spin-echo study. Both of the fast MR techniques yielded a fourfold reduction in imaging time per section. The advanced Fourier sequence showed contrast that was identical to the conventional spin-echo study with signal-to-noise ratios of 58% and 57% for the first and second echoes, respectively. The partial-flip sequence showed a contrast of 109% and 57% for lesions versus substantia alba, and 107% and 78% for substantia grisea versus substantia alba relative to the first and second echoes of the conventional spin-echo study. The partial-flip sequence was particularly sensitive to magnetic susceptibility; this produced artifacts that may undermine the usefulness of partial flip for routine screening in certain parts of the brain. However, this susceptibility significantly improved the detection of intracranial hemorrhage when compared with the spin-echo sequence, particularly when combined with phase mapping of the partial-flip study.     

Pentobarbital pharmacokinetics in patients with severe head injury

Intravenous administration of high-dose pentobarbital has been proposed as a treatment for elevated intracranial pressure refractory to other measures in brain-injured patients. The purpose of this clinical study was to examine the pharmacokinetics of high-dose continuous intravenous infusion of pentobarbital in this critical care setting. Six patients received a 25-34 mg/kg intravenous loading dose followed by a 1-3 mg/kg/h continuous infusion for 61-190 hours. Dosing rates were adjusted based on the patient's clinical status. The mean clearance was 0.72 ml/min/kg, with a volume of distribution (Vd) of 1.03 L/kg and a terminal half-life of 19.1 h. Considerable variation in individual patient parameters was observed. In addition, a change in clearance was suggested in patients requiring a longer infusion duration.     

高效液相色谱法测定右旋儿茶素血浆浓度及药代动力学参数

本文建立了体液中右旋儿茶素的RP-HPLC测定方法。采用C_(18)键合相硅胶为填料的固相提取柱进行样品预处理,右旋儿茶素的提取回收率为79.8%.应用二极管阵列检测器对色谱峰纯度进行鉴定。该法精密度好,方法回收率近100%,日内、日间的变异系数为2.4～5.6%,血浓69.6～1160 ng/ml范围内呈线性关系,r=0.9993。家兔静注右旋儿茶素18mg/kg,其药代动力学过程符合二室模型,分布相半衰期为0.129 h,消除相半衰期为1.19h。     

A randomized comparison of umbilical vein and intravenous oxytocin during the puerperium

Oxytocin was administered in a randomized fashion via either the umbilical or maternal intravenous route. Women who received intraumbilical oxytocin had significantly greater calculated blood loss compared with those who received peripheral administration (P = .01). This greater blood loss was confirmed by a decrease in hematocrit and hemoglobin concentrations after delivery. There was no difference between the groups in the length of the third stage of labor. The incidence of fetomaternal transfusion was higher in the intraumbilical group (P = .07). We conclude that intraumbilical oxytocin is no more beneficial than peripheral administration.