Sándor Pintér

Impaired early neurologic outcome in newborn piglets reoxygenated with 100% oxygen compared with room air after pneumothorax-induced asphyxia

Birth asphyxia is a serious problem worldwide, resulting in 1 million deaths and an equal number of neurologic sequelae annually. It is therefore important to develop new and better ways to treat asphyxia. In the present study we tested the effects of reoxygenation with room air or with 100% oxygen (O2) after experimental pneumothorax-induced asphyxia on the blood oxidative stress indicators, early neurologic outcome, and cerebral histopathology of newborn piglets. Twenty-six animals were studied in three experimental groups:1) sham-operated animals (SHAM, n = 6), 2) animals reoxygenated with room air after pneumothorax (R21, n = 10), and 3) animals reoxygenated with 100% O2 after pneumothorax (R100, n = 10). In groups R21 and R100, asphyxia was induced under anesthesia with bilateral intrapleural room air insufflation. Gasping, bradyarrhythmia, arterial hypotension, hypoxemia, hypercarbia, and combined acidosis occurred 62 ± 6 min (R21) or 65 ± 7 min (R100; mean ± SD) after the start of the experiments; then pneumothorax was relieved, and a 10-min reoxygenation period was started with mechanical ventilation with room air (R21) or with 100% O2 (R100). The newborn piglets then breathed room air spontaneously during the next 3 h. Blood oxidative stress indicators (oxidized and reduced glutathione, plasma Hb, and malondialdehyde concentrations) were measured at different stages of the experiments. Early neurologic outcome examinations (neurologic score of 20 indicates normal, 5 indicates brain-dead) were performed at the end of the study. The brains were next fixed, and various regions were stained for cerebral histopathology. In the SHAM group, the blood gas and acid-base status differed significantly from those measured in groups R21 and R100. In group R100, arterial Po2 was significantly higher after 5 (13.8 ± 5.6 kPa) and 10 min (13.2 ± 6.3 kPa) of reoxygenation than in group R21 (8.7 ± 2.8 kPa and 9.2 ± 3.1 kPa). The levels of all oxidative stress indicators remained unchanged in the study groups (SHAM, R21, and R100). The neurologic examination score in the SHAM group was 18 ± 0, in group R21 it was 13.5 ± 3.1, and in group R100 it was 9.5 ± 4.1 (significant differences between SHAM and R21 or R100, and between R21 and R100). Cerebral histopathology revealed marked damage of similar severity in both asphyxiated groups. We conclude that the blood oxidative stress indicators and cerebral histopathology did not differ significantly after a 10-min period of reoxygenation with room air or with 100% O2 after pneumothorax-induced asphyxia, but reoxygenation with 100% O2 might impair the early neurologic outcome of newborn piglets.

Nonenzymatic antioxidants of blood in multiple sclerosis

Abstract Free radical action has been suggested as a causal factor in multiple sclerosis. We investigated the plasma level of lipid peroxides expressed in terms of malone dialdehyde and changes in blood nonenzymatic antioxidants (glutathione, α-tocopherol, retinol, plasma sulfhydryl groups, and uric acid) in multiple sclerosis patients with exacerbation or in remission, including a group treated with β-interferon. The malone dialdehyde level was increased by 38% (n.s.) during exacerbations. The blood concentration of oxidized glutathione was likewise elevated (P < 0.05), while the ratio of plasma α-tocopherol to cholesterol plus triglyceride was decreased (P < 0.001). These changes suggest increased free radical production and consumption of the scavenger molecules during the active phase of the disease. Blood reduced glutathione level was increased (P < 0.01) during exacerbation and remission as well. The rise in this thiol is likely to be a compensatory mechanism defending the cells from further oxidant injuries. β-Interferon increased plasma α-tocopherol levels (P < 0.001) but not the lipid corrected α-tocopherol value. Other parameters were not influenced by the drug.

Delayed riluzole treatment is able to rescue injured rat spinal motoneurons.

The effect of delayed 2-amino-6-trifluoromethoxy-benzothiazole (riluzole) treatment on injured motoneurons was studied. The L4 ventral root of adult rats was avulsed and reimplanted into the spinal cord. Immediately after the operation or with a delay of 5, 10, 14 or 16 days animals were treated with riluzole (n=5 in each group) while another four animals remained untreated. Three months after the operation the fluorescent dye Fast Blue was applied to the proximal end of the cut ventral ramus of the L4 spinal nerve to retrogradely label reinnervating neurons. Three days later the spinal cords were processed for counting the retrogradely labeled cells and choline acetyltransferase immunohistochemistry was performed to reveal the cholinergic cells in the spinal cords. In untreated animals there were 20.4+/-1.6 (+/-S.E.M.) retrogradely labeled neurons while in animals treated with riluzole immediately or 5 and 10 days after ventral root avulsion the number of labeled motoneurons ranged between 763+/-36 and 815+/-50 (S.E.M.). Riluzole treatment starting at 14 and 16 days after injury resulted in significantly lower number of reinnervating motoneurons (67+/-4 and 52+/-3 S.E.M., respectively). Thus, riluzole dramatically enhanced the survival and reinnervating capacity of injured motoneurons not only when treatment started immediately after injury but also in cases when riluzole treatment was delayed for up to 10 days. These results suggest that motoneurons destined to die after ventral root avulsion are programmed to survive for some time after injury and riluzole is able to rescue them during this period of time.

Surface Tension, Glutathione Content and Redox Ratio of the Tracheal Aspirate Fluid of Premature Infants with IRDS

Objective: Determination of the surface tension (ST), the total glutathione (GL) content and the ratio of oxidized glutathione (GSSG) to reduced glutathione (GSH) in the tracheal aspirate (TA) of newborn infants with IRDS. Methods: The ST of the TA was determined by monitoring the fluid level pulsated in a capillary glass tube by means of a digitalized videocomputerized picture analysis program, a technique developed in our laboratory. The concentrations of GSSG and total GL in the TA were determined enzymatically with glutathione reductase. All results of laboratory tests were referred to the total phospholipid (PL) concentration. Patients, Experimental Material: TA samples were collected from 32 intubated premature and newborn infants admitted to the NICU with IRDS during the first 2 weeks of their lives. Control samples were obtained from 11 children prior to elective surgery. Results: The ST relative to the PL content (surface tension index, STI) was significantly lower in the newborns with IRDS than in the control group, and the concentration of GSH in the TA was also markedly decreased in all IRDS infants studied. The concentration of GSSG and the ratio of GSSG to GSH were significantly higher in the severe cases and in those with an unfavourable prognosis. Surfactant treatment had a protective effect against oxidative stress, it induced a decrease in both the GSSG concentration and in the GL redox ratio (GSSG/GSH) in the TA. There was a close correlation between the GSH content and the STI value of the samples studied. Conclusion: Oxidation and consequent depletion of GSH in the TA may be an aggravating factor in the development of the insufficient surface activity in intubated newborns with IRDS.

Increased survival and reinnervation of cervical motoneurons by riluzole after avulsion of the C7 ventral root

Although adult motoneurons do not die if their axons are injured at some distance from the cell body, they are unable to survive injury caused by ventral root avulsion. Some of the injured motoneurons can be rescued if the ventral root is re-inserted into the spinal cord. Brachial plexus injuries that involve the complete or partial avulsion of one or more cervical ventral roots can be treated successfully only if satisfactory numbers of motoneurons remain alive following such an injury at the time of reconstructive surgery. Here we investigated the various strategies that could be used to rescue injured rat cervical motoneurons. The seventh cervical ventral root (C7) was avulsed and various therapeutic approaches were applied to induce motoneuronal survival and regeneration. Avulsion of the root without reimplantation resulted in very low numbers of surviving motoneurons (65 ± 8 SEM), while treatment of the injured motoneurons with riluzole resulted in high numbers of surviving motoneurons (637 ± 26 SEM). When the C7 ventral root was reimplanted or a peripheral nerve implant was used to guide the regenerating axons to a muscle, considerable numbers of motoneurons regenerated their axons (211 ± 15 SEM and 274 ± 28 SEM, respectively). Much greater numbers of axons regenerated when reimplantation was followed by riluzole treatment (573 ± 9 SEM). These results show that injured adult motoneurons can be rescued by riluzole treatment, even if they cannot regenerate their axons. Reinnervation of the peripheral targets can also be further improved with riluzole treatment.

Does obstetric brachial plexus injury influence speech dominance

Right‐handedness and left‐sided language lateralization is an unresolved mystery with unknown cause/effect relations. Most studies suggest that the language lateralization is related to a fundamental brain asymmetry: right‐handedness may be secondary. We analyzed the possibility of an opposite cause/effect relation: whether asymmetric hand usage (as a cause) can influence language lateralization (as a consequence).

Regeneration of Reinnervated Rat Soleus Muscle Is Accompanied by Fiber Transition Toward a Faster Phenotype

The functional recovery of skeletal muscles after peripheral nerve transection and microsurgical repair is generally incomplete. Several reinnervation abnormalities have been described even after nerve reconstruction surgery. Less is known, however, about the regenerative capacity of reinnervated muscles. Previously, we detected remarkable morphological and motor endplate alterations after inducing muscle necrosis and subsequent regeneration in the reinnervated rat soleus muscle. In the present study, we comparatively analyzed the morphometric properties of different fiber populations, as well as the expression pattern of myosin heavy chain isoforms at both immunohistochemical and mRNA levels in reinnervated versus reinnervated-regenerated muscles. A dramatic slow-to-fast fiber type transition was found in reinnervated soleus, and a further change toward the fast phenotype was observed in reinnervated-regenerated muscles. These findings suggest that the (fast) pattern of reinnervation plays a dominant role in the specification of fiber phenotype during regeneration, which can contribute to the long-lasting functional impairment of the reinnervated muscle. Moreover, because the fast II fibers (and selectively, a certain population of the fast IIB fibers) showed better recovery than did the slow type I fibers, the faster phenotype of the reinnervated-regenerated muscle seems to be actively maintained by selective yet undefined cues.

Loss of capsaicin-induced meningeal neurogenic sensory vasodilatation in diabetic rats

Neuropathic alterations of sensory nerves involved in the mediation of neurogenic inflammation of the meninges may contribute to the increased incidence of headaches in diabetics. In the rat, activation of capsaicin-sensitive nociceptors, which express the transient receptor potential vanilloid type 1 (TRPV1) receptor, induces meningeal vasodilatation, a significant component of neurogenic inflammation, through the release of calcitonin gene-related peptide (CGRP). This study examines the effects of streptozotocin-induced diabetes on TRPV1 receptor-mediated neurogenic sensory vasodilatation, CGRP release and nerve fiber density in the rat dura mater. In a cranial window preparation, epidural application of capsaicin (10(-7) M) produced distinct vasodilatory responses in control animals as measured by laser Doppler flowmetry. In diabetic rats, capsaicin-induced vasodilatation was reduced or even abolished 6, but not 2 or 4 weeks after diabetes induction. In contrast, vasoconstriction, a non-neurogenic response to capsaicin at a higher concentration (10(-5) M), was not altered in diabetic rats. The vasodilatory effects of histamine (10(-5) M), acetylcholine (10(-4) M) and CGRP (10(-5) M) were similar in control, diabetic and insulin-treated diabetic animals. In diabetic rats, a significant decrease in the capsaicin-evoked release of CGRP and reduction in the density of TRPV1-immunoreactive (IR) nerves were demonstrated. Treatment of the diabetic rats with insulin restored both the vasodilatory response and the capsaicin-induced CGRP release toward control values. In conclusion, this study revealed a marked impairment of meningeal TRPV1-IR nerves in streptozotocin diabetic rats by showing reduced neurogenic sensory vasodilatation, decreased capsaicin-evoked CGRP release and reduction in the number of TRPV1-IR nerve fibers of the dura mater. The findings suggest that capsaicin-sensitive afferents may play an important role in meningeal nociceptor function and their dysfunction, e.g. due to a limited removal of inflammatory mediators and/or tissue metabolites from the meningeal tissue, may contribute to the enhanced incidence of headaches in diabetics.

Inhibitory effects of methylxanthines on the pre-eclamptic-like symptoms in ewes

OBJECTIVE Our objective was to determine whether two methylxanthines, pentoxifylline (PTX) and allopurinol, would have beneficial effects on experimental pregnancy-induced pre-eclampsia- like disease in ewes. STUDY DESIGN 20 animals at the gestational age of 130-135 days were divided into four groups (control; fasting; fasting, pentoxifylline-treated; and fasting, allopurinol-treated). The illness was provoked with a 4-day fasting period. Electrolytes, glucose, conventional parameters, plasma haem content, indirect bilirubin concentration and free thiol levels were measured. RESULTS Unlike in the fasting group, conventional signs of the disease, such as hypertension, kidney and liver injury and platelet count decrease, were all mitigated in the fasting, drug-treated animals. In the treated animals plasma haem content increased by a less significant level, while indirect bilirubin concentration showed a more rapid rise. CONCLUSIONS Both methylxanthines partly inhibited the pre-eclamptic-like symptoms in ewes. We speculate that the better induction of haem oxygenase might play an important role in this inhibitory effect on this particular animal model.

Postasphyxial Reoxygenation Reduces the Activity of Na+/K+-ATPase in the Erythrocytes of Newborn Piglets

The aim of our study was to determine whether the impairment of Na⁺/K⁺ pump is detectable in erythrocytes during hypoxia and reoxygenation. Acute asphyxia was induced in 10 newborn piglets for 1 h by bilateral pneumothorax. The Na⁺/K⁺-ATPase activity, Na⁺, K⁺ and ATP content of RBCs were determined in baseline condition (p_aO₂: 60.4 ± 9.3 mm Hg), at the end of the hypoxic period (1 h) (p_aO₂: 30.2 ± 10.3 mm Hg), then hourly during the reoxygenation phase (2, 3, 4 h) (p_aO₂: 54.8 ± 9.0, 56.1 ± 8.7, 57.2 ± 9.6 mm Hg). The Na⁺/K⁺-ATPase activity was constant during the first 3 h. However, it decreased at 4 h (676 ± 168 versus baseline 833 ± 141 U, p < 0.05). The highest ATP content was measured also at this point (4.32 ± 0.57 versus baseline 3.27 ± 0.45 mmol/l RBC, p < 0.01). The Na⁺ content was lower at 1 and 2 h (14.0 ± 1.8; 13.8 ± 1.2 versus baseline 15.7 ± 1.2 mmol/100 g Hb, p < 0.05), but later it became normal. Plasma monovalent cationic levels and intracellular K⁺ content did not alter during the experiment. Our results indicate that the deterioration of enzyme activity occurs within the same time-frame that previously described morphological alterations in brain tissue develop, so the RBC Na⁺/K⁺-ATPase activity might reflect the progress of posthypoxial brain damage.