A study on early-onset neonatal group B streptococcal infection, Bulgaria, 2007-2011.

This study examines neonatal group B streptococcal (GBS) colonization and its relation to early-onset GBS disease (EOGBSD), based upon the experience of leading obstetrics and gynecology centers in Bulgaria. The objectives of the study were to update neonatal colonization rates and to assess relationships between clinically differentiated cases (culture-proven GBS newborns) and risk factors inherent to the infant and mother, using a computerized file. The neonatal GBS colonization rate ranged from 5.48 to 12.19 per 1000 live births. Maternal-fetal infection (MFI, a provisional clinical diagnosis in culture-proven colonized infants with initial signs of infection that is usually overcome with antibiotic treatment) and/or intrapartum asphyxia (IA) have been demonstrated as the most frequent clinical manifestations, with significant correlations for the primary diagnosis, but not affirmative for the final diagnosis at discharge, resulting from adequate treatment of neonates. MFI and IA were significantly related to prematurity, and reciprocally, prematurity was associated with the risk of MFI, indirectly suggesting that preterm birth or PPROM (preterm premature rupture of membranes, an obstetric indication associated with early labor and delivery, one of the major causes of preterm birth) is a substantial risk factor for EOGBSD. The regression analysis indicated that in the case of a newborn with MFI, a birth weight 593.58 g lower than the birth weight of an infant without this diagnosis might be expected. Testing the inverse relationship, i.e., the way birth weight influences a certain diagnosis (logistic regression) established the presence of a relationship between birth weight categories (degree of prematurity) and the diagnosis of MFI. The proportions and odds ratios, converted into probabilities that a baby would develop MFI, indicate the particularly high risk for newborns with extremely low and very low birth weight: extremely low birth weight (≤1000 g), the probability of developing a MFI is 66%; very low birth weight (1001-1500 g), 81%; low birth weight (the birth weight category including premature and small for gestational age term infants: 1501-2500 g), 40%; normal birth weight (term infants) (>2500 g), 32%. In conclusion, the need to introduce separate categories for early- and late-onset GBS disease in the registration nomenclature of neonatal infectious diseases is highlighted by these results. Drawing up intrapartum antibiotic prophylaxis (IAP) guidelines is also strongly recommended.

Vibration stimulation during non-fatiguing tonic contraction induces outlasting neuroplastic effects.

The objective was to explore if vibration superposed to tonic contraction induces plastic changes in the contra- and ipsilateral motor cortex. Healthy subjects (n=12) abducted the right index finger with a force 5% of maximal voluntary contraction (MVC) against the lever of a torque motor while a 60 Hz vibration stimulus of 10 min was delivered. Motor evoked potentials (MEPs) after single and paired-pulse transcranial magnetic stimulation (TMS) were recorded from the first dorsal interosseous muscle of right and left hand pre, during, post and 30 min post-stimulation. The TMS assessments were employed with tonic contraction alone (TONIC) and with superposed vibrostimulation (VIBRO), each for the ipsi- and contralateral cortex separately. In the contralateral cortex: resting motor threshold (rMT) decreased, MEP amplitudes increased, short-interval intracortical inhibition (SICI) reduced and intracortical facilitation (ICF) increased post VIBRO, while no changes occurred post TONIC. In the ipsilateral cortex: rMT decreased, MEP amplitude increased and SICI reduced during TONIC, while no changes occurred post TONIC, during and post VIBRO. Vibration superposed to tonic contraction, induces lasting (30 min) plastic changes, whereas contraction alone caused no outlasting effects. Mainly intrinsic intracortical mechanisms are involved because spinal adaptation could be excluded (F-wave assessments). These findings have a therapeutic potential in the functional recovery of motor deficits with robot-aided devices.

Motor cortex excitability during unilateral muscle activity.

The effect of unilateral tonic muscle activity with and without co-activation of the antagonists on motor cortex excitability has been studied. Motor evoked potentials (MEPs) were recorded from the first dorsal interosseus muscles of both hands in response to transcranial magnetic stimulation (TMS) during relax, isometric index finger abduction and antagonistic co-activation. The intracortical inhibition (ICI) and intracortical facilitation (ICF) were investigated by paired-pulse TMS with interstimulus intervals of 3 and 13 ms. The unilateral tonic activation of the right hand facilitated contralateral and ipsilateral responses (cMEP and iMEP) recorded from both hands with an exception of iMEPs recorded from the left hand. During paired-pulse TMS ICI for cMEPs was not influenced by the unilateral tonic activity in both hands, while ICF was suppressed when MEPs were recorded from the active right hand. The effect of unilateral tonic activity on iMEP in response to paired-pulse TMS was essentially different: generally, ICI was greater for iMEPs and ICF was completely abolished with an exception of iMEPs recorded from the left hand during right finger isometric abduction when a strong ICF was evident. The decreased ICF and/or increased ICI are assumed to reflect mechanisms underlying the co-activation of antagonists.

Electron density and gas temperature from line broadening in an argon surface-wave-sustained discharge at atmospheric pressure.

We have used the collisional broadening of neutral argon lines to determine the electron density and gas temperature of a microwave discharge at atmospheric pressure. The gas temperature can be obtained from the Van der Waals broadening, provided that the Stark broadening is negligible. This can be achieved by using lines from low-lying levels (close to the ground state). On the other hand, lines corresponding to transitions from high-lying levels, which are more sensitive to Stark (quadratic) broadening, can be utilized to determine electron density. The electron density values obtained from the quadratic Stark broadening of argon atoms are in reasonable agreement with those derived from the linear Stark broadening of the H(beta) line. The proposed method ensures perturbation-free access to plasma parameters, which is not the case when adding hydrogen to the discharge, even in a small amount, to observe the Balmer series lines.

A histochemical method for demonstration of 2',3'-cyclic 3'-phosphohydrolase activity.

A histochemical method for demonstration of 2',3'-cyclic nucleotide 3'-phosphohydrolase activity is proposed. Cryostat sections, fixed in chlorophorm-methanol mixture, are incubated in a solution containing cyclic adenosine 2',3'-monophosphate, acid phosphatase, lead nitrate in acetate buffer, pH = 6,4 or 6.5. This method is based on conversion by the 2',3'-cyclic nucleotide 3'-phosphohydrolase of cyclic adenosine 2',3'-monophosphate to nucleotide-2'-monophosphate. Under the action of exogenous acid phosphatase, inorganic phosphate is released. It precipitates as lead phosphate if lead ions are present. By adding yellow ammonium sulphide, the lead phosphate is converted to lead sulphide which is the visible reaction product.