Lipoteichoic acid from Streptococcus sanguis is a natural glucosyl acceptor for glucosyltransferases

The synthesis of methanol insoluble-[14C]labeled-polymers from [14C]sucrose by S. mutans glucosyltransferases was stimulated up to four-fold by the presence of highly purified, lipoteichoic acid (LTA) from S. sanguis. Gel filtration chromatography (Sepharose 4B) and ion exchange chromatography (DEAE-Bio-Gel A) of the [14C]labeled-polymers formed in the presence of [3H]glycerol-labeled-LTA showed that high molecular weight, negatively charged [14C]labeled-[3H]glycerol-labeled-LTA complexes were being formed. The [14C]component was identified as glucose by acid hydrolysis and paper chromatography. A similar high molecular weight, negatively charged [14C]glucosyl-[3H]glycerol-labeled-polymer was extracted from S. mutans cells grown in the presence of [3H]glycerol and [14C]sucrose, suggesting that LTA is a glucosyl-acceptor for glucosyltransferases in vivo as well as in vitro.

Subunit- and brain region-specific reduction of GABAA receptor subunit mRNAs during chronic treatment of rats with diazepam

The mRNA levels for several GABAA receptor subunits were measured by Northern blot analysis. Rats were treated for 3 wk by continuous release of diazepam (DZP) from subcutaneous reservoirs, and then sacrificed immediately or 48 h after removing the reservoirs. Poly(A)+ RNAs, isolated from cerebral cortex, cerebellum, and hippocampus, were hybridized with oligonucleotide probes for GABAA receptor subunits and a cDNA probe for beta-actin. Subunit mRNAs were expressed relative to the corresponding beta-actin mRNA. DZP treatment decreased the alpha 1 subunit mRNA level 40% in hippocampus, but it was not changed in cortex or cerebellum. The alpha 5 subunit mRNA level was decreased in cerebral cortex (28%) and hippocampus (15%). The gamma 2 subunit mRNA level was decreased (40%) only in cortex. DZP treatment did not affect alpha 2, alpha 3, alpha 4, beta 2, or beta 3 subunit mRNA levels. Decreases in mRNA levels had reversed within 48 h after stopping chronic treatment. Acute DZP did not change alpha 1, alpha 5, or gamma 2 subunit mRNA levels. The decreases in GABAA receptor subunit mRNA levels were specific to subunit and brain region. These results, coupled with those after chronic flurazepam treatment, also indicated that the effects on GABAA receptor subunit mRNA levels are specific to the benzodiazepine (BZ) used for chronic treatment.

alpha-Fetoprotein levels of paired samples between the amniotic fluid and maternal serum from 16 to 18 weeks' gestation in Chinese women

To assess the relationship between alpha-fetoprotein (AFP) concentrations of amniotic fluid and maternal serum from 16 to 18 weeks' gestation, 890 paired samples of maternal serum and amniotic fluid were collected from women with normal singleton pregnancies. The gestational age was determined by ultrasonographic dating before amniocentesis, and the AFP measurements were performed by a single reference laboratory. There was a significant rise in the maternal serum AFP (MSAFP) concentration from 16 to 18 weeks' gestation. Amniotic fluid AFP concentrations significantly declined from 16 to 18 weeks' gestation. This study failed to demonstrate any statistical relationship between the AFP concentration of maternal serum and amniotic fluid (r = 0.031). This finding indicates that amniotic fluid AFP levels cannot be predicted by MSAFP levels between 16 and 18 weeks' gestation. Simple diffusion may not be the only mechanism for the transfer of AFP through the fetal membrane to maternal circulation.

Differential regulation of superoxide dismutase in copper-deficient rat organs

The effects of dietary copper deprivation on the activities, immunoreactive protein concentrations, and mRNA abundance of copper/zinc- and manganese-superoxide dismutase (Cu/Zn- and Mn-SOD) were examined in liver, heart, and brain of weanling rats fed a Cu-deficient diet for 4 weeks. Hepatic Cu/Zn-SOD activity, enzyme content, and mRNA abundance were significantly reduced, and, conversely, the activity, protein, and mRNA levels of Mn-SOD were significantly elevated in Cu-deficient rats. In Cu-deficient heart, the activity and protein content for Cu/Zn-SOD were reduced, whereas those for Mn-SOD were increased; the levels of mRNAs for these two enzymes was unaffected. Dietary Cu deficiency was without effect on the activities, enzyme contents, and mRNA abundance of brain Cu/Zn- and Mn-SOD. These results indicate that SODs from liver, heart, and brain exhibit differential sensitivities to dietary Cu deprivation, and that different mechanisms (transcriptional, posttranscriptional, or posttranslational) may be involved in their regulation.

Time-to-space mapping of femtosecond pulses

We report time-to-space mapping of femtosecond light pulses in a temporal holography setup. By reading out a temporal hologram of a short optical pulse with a continuous-wave diode laser, we accurately convert temporal pulse-shape information into a spatial pattern that can be viewed with a camera. We demonstrate real-time acquisition of electric-field autocorrelation and cross correlation of femtosecond pulses with this technique.

Reduced expression of gamma-aminobutyric acid type A/benzodiazepine receptor gamma 2 and alpha 5 subunit mRNAs in brain regions of flurazepam-treated rats

Previous studies showed that chronic benzodiazepine administration in rats affected the gamma-aminobutyric acid (GABA)A/benzodiazepine receptor. The present experiment investigated the effects of chronic flurazepam treatment on the mRNA levels for alpha 1, alpha 5, gamma 2, and gamma 2L (an alternatively spliced product of the gamma 2 gene) subunits of the GABAA/benzodiazepine receptor in rat cerebral cortex, cerebellum, and hippocampus. Rats were treated with flurazepam for 2 or 4 weeks, and the mRNA levels were measured while rats were still receiving drug or 48 hr after 4-week flurazepam treatment had been stopped. The level of alpha 5 mRNA was also measured in other rats 4 hr after a single injection of flurazepam or diazepam. The levels of mRNAs were analyzed by Northern blotting using digoxigenin-labeled oligonucleotide probes. Compared with the pair-handled controls, the levels of gamma 2 subunit mRNA in cortex and hippocampus were not changed after flurazepam treatment for 2 weeks. However, with rats treated with flurazepam for 4 weeks the levels of gamma 2 subunit mRNA were significantly reduced in cortex (31%) and hippocampus (39%) but not in cerebellum. The values returned to control levels by 48 hr after termination of the treatment. The regional distribution and time course of reduced gamma 2 levels matched the decrease in benzodiazepine binding produced by the same chronic flurazepam treatment. The amounts of alpha 5 mRNA were reduced in cortex (23%) and hippocampus (18%) 4 hr after a single dose of flurazepam but not diazepam. The levels of alpha 5 mRNA remained reduced in cerebral cortex and hippocampus (about 50%) after 2 weeks but returned to control after 4 weeks of chronic treatment with flurazepam. No change in alpha 1 or gamma 2L subunit mRNAs was observed in any of the three brain regions examined after 4 weeks of flurazepam treatment. These results suggest that benzodiazepine receptor down-regulation after chronic benzodiazepine treatment may be related to the reduced expression of gamma 2 subunit mRNA, and they also suggest differential temporal and regional regulation of alpha 5 and gamma 2 subunit mRNAs in rat brain.

Regional changes in [3H]zolpidem binding to brain benzodiazepine receptors in flurazepam tolerant rat: comparison with changes in [3H]flunitrazepam binding

Regional downregulation of brain benzodiazepine (BZ) receptors was studied in rats treated with flurazepam or diazepam protocols known to produce anticonvulsant tolerance. Zolpidem, a selective BZ1 receptor agonist, was used to detect BZ1 receptors; flunitrazepam, a nonselective BZ receptor agonist, was used to detect the total BZ receptor population. Rats were treated 4 weeks with flurazepam, then sacrificed immediately or 48 hr later. After flurazepam treatment, the maximal binding capacity of [3H]zolpidem binding decreased 22% in the cerebral cortex, 32% in the cerebellum and 25% in the hippocampus. The Kd increased in the cerebellum. The maximal binding capacity of [3H]flunitrazepam binding decreased by 13% in the cerebral cortex and 14% in the hippocampus, but did not change in the cerebellum. The Kd increased in the hippocampus. At 48 hr after flurazepam treatment, there was no significant difference in [3H]zolpidem binding between treated and control rats. In rats treated 3 weeks with diazepam released from s.c. reservoirs, there was no change in [3H]zolpidem binding. The data suggest that chronic flurazepam treatment causes downregulation primarily involving BZ1 receptors. The differing effects on [3H]-zolpidem and [3H]flunitrazepam binding, especially in the cerebellum in which more than 90% of the receptors are the BZ1 subtype, may indicate a shift in BZ receptor subtypes in flurazepam-tolerant rats, suggesting a change in the subunit composition or conformation of gamma-aminobutyric acidA/BZ receptors.

Actions of a long-acting somatostatin analog SMS201-995 (sandostatin) on rat locus coeruleus neurons

The actions of sandostatin involving rat locus coeruleus (LC) neurons were examined using an intracellular recording in a brain slice preparation. Bath application of sandostatin (5-100nM) reversibly decreased the firing rate of all neurons tested in a dose-dependent manner. Sandostatin was 9.5 times more potent than somatostatin in light of an inhibition of the spontaneous firing rate. In addition to the inhibition of spontaneous firing, larger concentrations of sandostatin (30-100nM) also hyperpolarized the neurons of the locus coeruleus and simultaneously caused a reduction in input resistance. At the highest concentration (100nM) applied, sandostatin produced complete inhibition of firing of all neurons tested (n = 49); the inhibition was associated with a 11.6mV hyperpolarization (range 2.2-26.4 mV, n = 49) and a 21.8% reduction in input resistance (range 2.6-55.2%, n = 39). The voltage-current relationship of the resting cell revealed an inward-going rectification that became enhanced after the perfusion of sandostatin (100nM) for 5 min. The reversal potential for the sandostatin-induced hyperpolarization was -111 +/- 1 mV (n = 10), which is approximately the potassium equilibrium potential. This hyperpolarization was blocked by both caesium chloride and barium chloride. Our results also showed that sandostatin displayed an antagonistic action on mu opiate receptors. Both the somatostatin-agonistic and opiate-antagonistic activities of sandostatin were conclusively found to be stronger than those of somatostatin; in addition, the inhibitory actions of sandostatin on LC neurons were due to an opening of the inward-going rectification potassium channels.

Growth discordancy, birth weight, and neonatal adverse events in third trimester twin gestations

In order to understand the effects of intrauterine growth discordancy (15% or more birth weight difference), birth weight, and gestational age on the neonatal adverse events (including 1- or 5-min Apgar scores < 7, neonatal death, ICU admission, respiratory distress, hypoglycemia, hypocalcemia, perinatal infection, blood transfusion, and hyperbilirubinemia) in third trimester twin gestations, 279 consecutive twin pairs delivered from January 1986 to December 1991 were studied. Univariate analyses showed discordant twins were smaller than concordant twins in gestational age by 1.4 weeks (35.74 and 37.14 weeks respectively). When birth weight was compared, that of smaller (one with lower birth weight in a pair) discordant twins (1,951 g) was significantly lower than that of smaller concordant twins (2,423 g), while larger (one with higher birth weight in a pair) discordant twins (2,556 g) and concordant twins (2,594 g) showed no significant difference. Univariate analysis indicated there was a tendency for adverse events to occur in discordant twins, especially in the smaller twin. Through logistic regression analysis, it was found that birth weight and gestational age, but not discordancy, are the predictors of the occurrence of adverse events. A smaller twin weighing no more than 2,000 g has a 10 times greater risk to develop an adverse event as compared to a twin with a birth weight over 2,000 g and a similar gestational age; while a twin with a gestational age of less than 34 weeks has a 5 times greater risk than one 34 weeks or over with a similar birth weight.

Expression of alpha 1, alpha 5, and gamma 2 GABAA receptor subunit mRNAs measured in situ in rat hippocampus and cortex following chronic flurazepam administration

Prolonged benzodiazepine treatment of rats results in anticonvulsant tolerance in vivo. Studies of in vitro hippocampal slices following 1 wk flurazepam administration show reduced GABA-mediated inhibition in the CA1 region, and a decrease in GABAA agonist and benzodiazepine potency to inhibit CA1 pyramidal cell-evoked responses. To investigate the molecular basis of benzodiazepine tolerance in the hippocampus, in situ hybridization techniques were used to evaluate the expression of the mRNAs for the alpha 1, alpha 5, and gamma 2 subunits of the GABAA receptor in the hippocampal formation and frontal cortex of chronic flurazepam-treated rats. A discretely localized decrease in alpha 1, but not alpha 5 or gamma 2 mRNA expression was found in the CA1 region (35-40%) and in layers II-III and IV of cortex (50-60%) 2 d after cessation of flurazepam treatment. The decrease in the expression of alpha 1 subunit mRNA in cortex is similar to that reported following other chronic benzodiazepine treatment regimens. This is the first report of a reduction in alpha 1 subunit mRNA expression in the hippocampal formation.

Tolerance to the effects of diazepam, clonazepam and bretazenil on GABA-stimulated Cl- influx in flurazepam tolerant rats

The effect of chronic flurazepam treatment on the GABA (gamma-aminobutyric acid) receptor/chloride channel complex was studied using GABA-stimulated 36Cl- influx into brain microsacs, and its potentiation by diazepam, clonazepam and bretazenil. Rats were given flurazepam for 1 week, then microsacs were prepared from cerebral cortices of rats that were still receiving flurazepam, and from those that had stopped treatment 48 h earlier. Diazepam and clonazepam produced concentration-dependent increases in GABA-stimulated 36Cl- influx while bretazenil produced a much smaller effect, which did not reach statistical significance in the tissue from control rats. There was no significant change in the basal or 10 microM GABA-stimulated 36Cl- influx between control and treated groups. Tolerance was shown by a significantly reduced effect of diazepam and clonazepam to enhance GABA-stimulated 36Cl- influx in the tissue prepared from non-withdrawn rats. However, for both diazepam and clonazepam, there was no tolerance 48 h after chronic treatment. The results suggest that changes in the GABA receptor/Cl- channel complex on cerebral cortical neurons contribute to cross-tolerance from flurazepam to other benzodiazepines.

Electrophysiological actions of alfentanil: intracellular studies in the rat locus coeruleus neurones

1. The electrophysiological effects of alfentanil on 156 neurones of the rat locus coeruleus were investigated by use of intracellular recordings from the in vitro brain slice preparation. 2. Bath application of alfentanil (5-100 nM) reversibly decreased the firing rate of all neurones tested in a dose-dependent manner, with an IC50 4.1.nM. 3. Based on inhibition of the spontaneous firing rate, alfentanil was 22 times more potent than morphine. 4. At 100 nM, alfentanil produced a complete inhibition of firing of all neurones tested (n = 62); the inhibition was accompanied by a membrane hyperpolarization 17.0 +/- 0.8 mV (range 6.1-30.3 mV, n = 62) and a reduction in input resistance 26.4 +/- 1.7% (range 6.5-53%, n = 51). 5. The effects of alfentanil were antagonized by naloxone, with a dissociation equilibrium constant of 2.7 +/- 0.4 nM (n = 6). 6. The reversal potential for the alfentanil-induced hyperpolarization was -110 +/- 2 mV (n = 9), which is approximately the potassium equilibrium potential. 7. The alfentanil-induced hyperpolarization was blocked by caesium chloride and barium chloride. 8. These results indicate that alfentanil binds to mu-opioid receptors on the cell membrane of neurones of the locus coeruleus. This leads to opening of the inward-going rectification potassium channels, resulting in the observed hyperpolarization of the membrane.

Deep vein thrombosis during pregnancy

Antepartum deep vein thrombosis is quite rare in Chinese women during pregnancy. An adequate diagnosis and early treatment are extremely important as the deep vein thrombosis can embolize, in particular, to the pulmonary vasculature. We present a case of pregnancy at 36 weeks gestation complicated by deep vein thrombosis. The objective diagnosis of deep vein thrombosis for obstetric patients is the noninvasive Doppler ultrasound and plethysmography. An early diagnosis is important to reduce maternal and fetal risks related to embolization. Continuous therapy of low dose intravenous heparin is safe and effective during pregnancy.

Maternal renal artery Doppler flow-velocity waveform in preeclampsia. A preliminary report

By use of duplex Doppler ultrasonography, we preliminarily studied 30 normal pregnancies (control group) and 30 patients with preeclampsia (study group) before treatment. The peak systolic flow height to end diastolic flow height (S/D) ratio of the maternal right and left renal arteries of both groups were compared and analyzed. The results showed that there were no significant differences between the right and left renal arteries in either group, but unexpectedly the S/D ratio of the renal artery on both sides in preeclamptic patients was significantly lower than in normal pregnant women (mean +/- SD, 2.07 +/- .12 vs. 2.41 +/- .12, respectively, P < .001). The lower S/D ratio of the renal artery may reflect a decrease in renovascular resistance and an increase in renal perfusion. These findings were the reverse of what might be expected from an elevated vascular resistance and hypoperfusion model.

Biosynthesis and characterization of phosphatidylglycerophosphoglycerol, a possible intermediate in lipoteichoic acid biosynthesis in Streptococcus sanguis

A membrane enzyme preparation from Streptococcus sanguis was shown to convert sn-[14C]glycerol 3-phosphate and CDP-diacylglycerol (or deoxyCDP-diacylglycerol) into a series of progressively higher-molecular-weight [14C]oligophosphoglycerophospholipids in vitro. The first oligophosphoglycerophospholipid to accumulate (termed lipid-1) was purified to homogeneity; chemical analysis, gas-liquid chromatography and chemical degradation studies indicated the most likely structure to be phosphatidylglycerophosphoglycerol (PGpG). PGpG is formed directly from two molecules of phosphatidylglycerol (PG), one molecule of PG serving as a sn-glycerol 1-phosphate (pG) donor and the second serving as the pG acceptor, with co-production of diacylglycerol. These oligophosphoglycerophospholipids may be intermediates in the biosynthesis of lipoteichoic acids.

Neonatal status in cesarean section under epidural anesthesia with supplementary oxygen

Simple O2 mask has been used in patient under regional anesthesia for increasing the FiO2, especially in the aged and the pregnant. The relationships between maternal FiO2 and umbilical arterial (UA) and venous (UV) PO2, PCO2, pH, and neonatal Apgar score were studied in 45 patients receiving Cesarean section under epidural anesthesia. 2% xylocaine 18-20 ml with adrenaline 1:200,000 was used to attain the sensory level of T-4. Patients were allocated randomly into three groups. Group I, acting as a control group, breath only room air during the course of anesthesia. Group II was breathing through a simple face mask with an oxygen inflow of 6L/min. Group III was breathing oxygen with a flow rate of 10L/min through a simple face mask. UA and UV blood samples were collected separately at the time of delivery for blood gas analysis. The 1-min, and 5-min Apgar scores were recorded also. Mean values of the UA blood samples for the 3 groups (Gp. I, Gp. II and Gp. III respectively) were: PO2--16.50 mmHg, 20.20 mmHg and 19.50 mmHg; PCO2--49.20 mmHg, 48.10 mmHg and 50.3 mmHg; pH--7.31, 7.30 and 7.30. Mean values of the UV blood samples for the 3 groups (Gp. I, Gp. II and Gp. III respectively) were: PO2--28.6 mmHg, 36.9 mmHg and 36.5 mmHg; PCO2--38.20 mmHg, 38.80 mmHg and 40.40 mmHg; pH--7.36, 7.36 and 7.34. There was a significant increase in UA and UV PO2 when using a simple O2 mask (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Meconium peritonitis-antenatal diagnosis by ultrasound

Meconium peritonitis is usually the result of prenatal bowel obstruction with subsequent perforation, then the contents spread into the peritoneal cavity, which results in a sterile inflammatory reaction. The incidence ranges from 1/1500 to 1/2000, if without prenatal diagnosis and planned postnatal treatment, the mortality rate is as high as 62%. We describe three children, two with surgically, one with autoptically confirmed meconium peritonitis. All had abnormally prenatal ultrasonographic examinations. The first fetus showed a large 10 x 11 cm intra-abdominal mass with floating echogenic substances inside and with an echogenic rim. The second showed increased echogenicity with dilated bowel in abdominal cavity in one of the twin, and the third had an intra-abdominal cyst with several echogenic bands inside, fetal ascites was also noted. It is remarkable that the ultrasonographic findings were different in the three children. Two of the three children survived postoperation, one died 3 hours later after induction out at 31 weeks of gestational age due to multiple congenital anomalies.

Effects of exogenous GM1 ganglioside on LTP in rat hippocampal slices perfused with different concentrations of calcium

Combined actions of GM1 ganglioside molecules and Ca2+ ions on long-term potentiation (LTP) of the hippocampal CA1 synapses were examined in slice preparations. Application of exogenous GM1 ganglioside significantly enhanced LTP. Antigenic blocking of endogenous GM1 ganglioside by applying anti-GM1 antiserum appeared to attenuate LTP. Exogenous GM1 treatment not only antagonized LTP suppression caused by low Ca2+ (1.0 microM) in the perfusion medium, but also amplified LTP at high Ca2+ (5.0 microM) condition. Thus, GM1 may stabilize intracellular calcium levels to enhance synaptic potentiation.