Data on subglottal pressure and SPL at varied vocal loudness and pitch in 8- to 11-year-old children

Phonation threshold pressure has been defined as the minimum subglottal pressure to generate phonation. Previous research has indicated that children may habitually employ higher subglottal pressures than adults. In the present investigation sound pressure level (SPL) and subglottal pressures at different pitch levels were measured at and above phonation threshold in nine children. Phonation threshold values were scattered in reasonable agreement with Titzes' prediction, although a discrepancy was noted regarding the frequency dependence in some voices. At normal conversational loudness and loudest level of phonation the children's Ps values were between two to four and four to eight times the predicted threshold values, respectively. At normal conversational loudness and habitual pitch subglottal pressures were lower than those previously observed for children, but similar to those found for female adults. The SPL in softest and loudest phonation were somewhat lower as compared to previous phonetogram data for children and for female adults. At normal loudness and habitual pitch the SPL values were similar to those of female adults. For a doubling of Ps mean SPL increased by 10.5 dB on the average.

Theiler's virus infection of perforin-deficient mice

Theiler's virus, a murine picornavirus, infects the central nervous systems of C57BL/6 mice and is cleared after approximately 10 days by a process which requires CD8+ cytotoxic T cells. We used perforin-deficient C57BL/6 mice to test the role of this protein in viral clearance. Perforin-deficient mice died from viral encephalomyelitis between days 12 and 18 postinoculation. They had high levels of viral RNA in their central nervous systems until the time of death. In contrast, viral RNA had disappeared by day 11 postinoculation in wild-type C57BL/6 mice. Cytotoxic T cells can kill infected cells by two main mechanisms: the secretion of the pore-forming protein perforin or the interaction of the Fas ligand with the apoptosis-inducing Fas molecule on the target cell. Our results demonstrate that clearance of Theiler's virus from the central nervous system in C57BL/6 mice is perforin dependent.

PTFE-encapsulated endovascular stent-graft for transjugular intrahepatic portosystemic shunts: experimental evaluation

PURPOSE

To evaluate the safety and efficacy of a stent-graft designed for a transjugular intrahepatic portosystemic shunt (TIPS), assess angiographic and hepatic biologic responses to polytetrafluoroethylene (PTFE)-encapsulated stents, and compare with a bare stent.

MATERIALS AND METHODS

Twelve TIPS (eight with flexible PTFE-encapsulated balloon-expandable stent-grafts and four control TIPS with bare Wallstents) were created in 12 pigs. Shunt venography was performed at 1-month intervals and necropsy of graft-containing animals at 1, 2, 3, 4, and 5 months. Control animals were sacrificed at 6 weeks. Detailed histopathologic analyses were performed.

RESULTS

The stent-grafts were readily deployed in all cases. Seven of eight graft TIPS remained fully patent during the follow-up period without luminal encroachment. Typical myofibrolasts proliferated on the abluminal surface of the graft, without extension into the lumen. No inflammatory reaction was present. Cellular overgrowth from the hepatic vein occluded the end of one graft at 3 months, partly related to rapid axial growth of that animal. The endoluminal surface of this shunt was otherwise patent. At 4-6 weeks, one control TIPS was occluded and the other three showed 45%-85% stenoses. No bile staining was seen in any case.

CONCLUSION

This PTFE-encapsulated stent-graft is biocompatible and safe to place. It markedly improves TIPS patency, providing almost uninterrupted, unimpeded patency in this model.

Role of macrophages during Theiler's virus infection

Theiler's virus, a murine picornavirus, causes a persistent infection of the central nervous system with chronic inflammation and primary demyelination. We examined the nature of infected cells at different times postinoculation (p.i.) with a combined immunocytochemistry-in situ hybridization assay. The virus was found in the gray matter of the brain, mostly in neurons, during the first week p.i. During the following weeks, the virus was present in the spinal cord, first in the gray and white matter, then exclusively in the white matter. Approximately 10% of infected cells were astrocytes at any time during the study. Infected oligodendrocytes were first noticed on day 14 p.i. and amounted to approximately 6% of infected cells. The number of infected macrophages increased with time and reached a plateau by day 21 p.i., when at least 45% of infected cells were macrophages. The role of blood-borne macrophages during infection was studied by depleting them with mannosylated liposomes containing dichloromethylene diphosphonate. The virus did not persist in the majority of the mice treated with liposomes. These mice showed only minimal mononuclear cell infiltration and no demyelination.

Comparison of remifentanil and fentanyl in patients undergoing craniotomy for supratentorial space-occupying lesions

BACKGROUND

Remifentanil hydrochloride is an ultra-short-acting, esterase-metabolized mu-opioid receptor agonist. This study compared the use of remifentanil or fentanyl during elective supratentorial craniotomy for space-occupying lesions.

METHODS

Sixty-three adults gave written informed consent for this prospective, randomized, double-blind, multiple-center trial. Anesthesia was induced with thiopental, pancuronium, nitrous oxide/oxygen, and fentanyl (n = 32; 2 micrograms.kg.-1. min-1) or remifentanil (n = 31; 1 mu.kg-1.min-1). After tracheal intubation, infusion rates were reduced to 0.03 microgram.kg-1.min-1 (fentanyl) or 0.2 microgram.kg-1.min-1 (remifentanil) and then adjusted to maintain anesthesia and stable hemodynamics. Isoflurane was given only after specified infusion rate increases had occurred. At the time of the first burr hole, intracranial pressure was measured in a subset of patients. At bone flap replacement either saline (fentanyl group) or remifentanil (approximately 0.2 microgram.kg-1.min-1) were infused until dressing completion. Hemodynamics and time to recovery were monitored for 60 min. Analgesic requirements and nausea and vomiting were observed for 24 h. Neurological examinations were performed before operation and on postoperative days 1 and 7.

RESULTS

Induction hemodynamics were similar. Systolic blood pressure was greater in the patients receiving fentanyl after tracheal intubation (fentanyl = 127 +/- 18 mmHg; remifentanil = 113 +/- 18 mmHg; P = 0.004). Intracranial pressure (fentanyl = 14 +/- 13 mmHg; remifentanil = 13 +/- 10 mmHg) and cerebral perfusion pressure (fentanyl = 76 +/- 19 mmHg; remifentanil = 78 +/- 14 mmHg) were similar. Isoflurane use was greater in the patients who received fentanyl. Median time to tracheal extubation was similar (fentanyl = 4 min: range = -1 to 40 min; remifentanil = 5 min: range = 1 to 15 min). Seven patients receiving fentanyl and none receiving remifentanil required naloxone. Postoperative systolic blood pressure was greater (fentanyl = 134 +/- 16 mmHg; remifentanil = 147 +/- 15 mmHg; P = 0.001) and analgesics were required earlier in patients receiving remifentanil. Incidences of nausea and vomiting were similar.

CONCLUSIONS

Remifentanil appears to be a reasonable alternative to fentanyl during elective supratentorial craniotomy.

Role of VP2 amino acid 141 in tropism of Theiler's virus within the central nervous system

Following intracranial inoculation, Theiler's virus causes either an acute encephalitis (strain GDVII) or a chronic demyelinating disease (strain DA). The DA strain sequentially infects the grey matter of the brain, the grey matter of the spinal cord, and, finally, the white matter of the spinal cord, where it persists in glial cells and causes demyelinating lesions. Analysis of the phenotype of recombinant viruses has shown that the viral capsid contains determinants for persistence and demyelination. Our previous studies showed that a Lys at position 141 of the VP2 capsid protein (VP2-141) could render a chimeric virus persistent. We also reported that another recombinant virus, virus R5, migrated from the grey matter of the brain to that of the spinal cord inefficiently and was unable to infect the white matter of the spinal cord. In this article, we report that introducing a Lys at position VP2-141 in virus R5 increases its ability to infect the white matter of the spinal cord. Our results indicate that this amino acid is important for the spread of the virus within the central nervous system.

Perturbation and hoarseness: a pilot study of six children's voices

Fundamental frequency (FO) perturbation has been found to be useful as an acoustic correlate of the perception of dysphonia in adult voices. In a previous investigation, we showed that hoarseness in children's voices is a stable concept composed mainly of three predictors: hyperfunction, breathiness, and roughness. In the present investigation, the relation between FO perturbation and hoarseness as well as its predictors was analyzed in running speech of six children representing different degrees of hoarseness. Two perturbation measures were used: the standard deviation of the distribution of perturbation data and the mean of the absolute value of perturbation. The results revealed no clear relation.

In vivo models of cerebral ischemia: effects of parenterally administered NMDA receptor glycine site antagonists

Both in vitro and in vivo experiments have implicated extracellular glycine in the pathogenesis of ischemic brain damage. Recently, halogenated derivatives of quinoxaline-2,3-dione have been synthesized that possess bioavailability when parenterally administered and minimal psychotomimetic properties. Such compounds have allowed investigation into the efficacy of glycine receptor antagonism as a strategy for protection against cerebral ischemic insults. Rats underwent either 90 min of middle cerebral artery filament occlusion or 10 min of forebrain ischemia with recovery while receiving intraperitoneal injections of either a glycine receptor antagonist (ACEA-1021, ACEA-1031, or ACEA-1011) or vehicle (dimethyl sulfoxide). Both ACEA-1021 and ACEA-1031 reduced cerebral infarct volumes and were associated with a reduced incidence of hemiparesis resulting from MCA occlusion. ACEA-1011, administered in a smaller dose had no effect. In the forebrain ischemia model, glycine receptor antagonism had no effect on delayed neuronal necrosis in the hippocampal CA1 sector, neocortex, or caudoputamen. We conclude that pharmacologic antagonism of glycine at the strychnine-insensitive glycine receptor presents a neuroprotective profile similar to that previously observed for antagonists of glutamate at the N-methyl-D-aspartate complex with a potential for fewer side effects.

Aetiologic factors associated with hoarseness in ten-year-old children

The parents of 55 10-year-old children answered questionnaires concerning 51 elements of potential relevance to voice function such as vocal habits, speech and language development, medical history, social history, physical environment and family relations. In addition, personality profiles of each child were assessed by its teacher and parents. The results were compared to an expert listening panel's evaluation of hoarseness and vocal-fold status as determined by a visual examination by a phoniatrician. Eight boys were identified as being chronically hoarse. Gender, personality and hours spent per day in large groups were highly significant factors associated with hoarseness. A discriminant analysis based on the significant background variables correctly grouped 86.3% of the children.

Relations between voice range profiles and physiological and perceptual voice characteristics in ten-year-old children

Pitch and intensity range of 60 children were recorded and plotted in voice range profiles (VRPs). Different aspects were investigated: minimum phonation threshold, pitch range, and maximum dynamic range. Vocal fold status was determined via laryngoscopic examination. Ten percent of the children had vocal nodules, 23% glottal chinks. Seven voice experts listened to the voices recorded on two separate occasions and rated their properties along 16 parameters including hoarseness. Fourteen percent were rated as hoarse on both recordings and were thus classified as being chronically hoarse. Departures from normal in VRP characteristics were found for children suffering from chronic hoarseness, nodules, and glottal chinks. Children in general seem to have somewhat compressed VRP contours compared with adults, reflecting restricted dynamic vocal capabilities; however, children with mutational voices exhibited an approximation to adult upper VRP contours.

Chimeric Theiler's virus with altered tropism for the central nervous system

Theiler's virus is a neurotropic murine picornavirus which, depending on the strain, causes either an acute encephalitis or a persistent demyelinating disease. Following intracranial inoculation, the demyelinating strains infect sequentially the grey matter of the brain, the grey matter of the spinal cord, and finally the white matter of the spinal cord, where they persist and cause chronic demyelination. The neurovirulent strains cause a generally fatal encephalitis with lytic infection of neurons. The study of chimeric Theiler's viruses, obtained by recombining the genomes of demyelinating and neurovirulent strains, has shown that the viral capsid contains determinants for persistence and demyelination. In this article we describe the recombinant virus R5, in which the capsid protein VP1 and a small portion of protein 2A come from the neurovirulent GDVII strain and the rest of the genome comes from the persistent DA strain. The capsid of virus R5 also contains one mutation at amino acid 34 of VP3 (Asn-->His). Virus R5 does not persist in the central nervous system (CNS) of immunocompetent SJL/J or BALB/c mice. However, it replicates efficiently and persists in the CNS of BALB/c nu/nu mice, showing that its growth in the CNS is not impaired. In BALB/c nu/nu mice, whereas virus DA causes mortality with large amounts of viral antigens in the white matter of the spinal cord, virus R5 does not kill the animals, persists in the neurons of the grey matter of the brain, and never reaches the white matter of the spinal cord. This phenotype is due to the chimerism of the capsid and/or to the mutation in VP3. These results indicate that the capsid plays an important role in the characteristic migration of Theiler's virus within the CNS.

A single amino acid change determines persistence of a chimeric Theiler's virus

The DA strain of Theiler's virus persists in the central nervous system of mice and causes chronic inflammation and demyelination. On the other hand, the GDVII strain causes an acute encephalitis and does not persist in surviving animals. Series of recombinants between infectious cDNA clones of the genomes of DA and GDVII viruses have been constructed. The analysis of the phenotypes of the recombinant viruses has shown that determinants of persistence and demyelination are present in the capsid proteins of DA virus. Chimeric viruses constructed by the different research groups gave consistent results, with one exception. Chimeras GD1B-2A/DAFL3 and GD1B-2C/DAFL3, which contain part of capsid protein VP2, capsid proteins VP3 and VP1, and different portions of P2 of GDVII in a DA background, were able to persist and cause demyelination. Chimera R4, whose genetic map is identical to that of GD1B-2A/DAFL3, was not. After exchanging the viral chimeras between laboratories and verifying each other's observations, new chimeras were generated in order to explain this difference. Here we report that the discrepancy can be attributed to a single amino acid difference in the sequence of the capsid protein VP2 of the two parental DA strains. DAFL3 (University of Chicago) and the chimeras derived from it, GD1B-2A/DAFL3 and GD1B-2C/DAFL3, contain a Lys at position 141, while TMDA (Institut Pasteur) and R4, the chimera derived from it, contain an Asn in that position. This amino acid is located at the tip of the EF loop, on the rim of the depression spanning the twofold axis of the capsid. These results show that a single amino acid change can confer the ability to persist and demyelinate to a chimeric Theiler's virus, and they pinpoint a region of the viral capsid that is important for this phenotype.

Anticoagulant effects of hirulog, a novel thrombin inhibitor, in patients with coronary artery disease

Selective thrombin inhibitors are a new class of antithrombotic drugs that, unlike heparin, can effectively inhibit clot-bound thrombin and escape neutralization by activated platelets. Hirulog is a 20 amino acid hirudin-based synthetic peptide that has shown promise in experimental models of thrombosis. Little information is available about the effects of hirulog in patients with coronary artery disease. Forty-five patients undergoing cardiac catheterization, who were taking aspirin, were randomized to receive either (1) hirulog, 0.05 mg/kg intravenous bolus followed by 0.2 mg/kg/hour intravenous infusion until the end of the catheterization; (2) hirulog, 0.15 mg/kg intravenous bolus followed by 0.6 mg/kg/hour intravenous infusion; or (3) heparin; 5,000 U intravenous bolus. Serial activated partial thromboplastin time (APTT), prothrombin time, activated clotting time and fibrinopeptide A were measured. Hirulog produced a dose-dependent prolongation of all coagulation parameters; the 0.6 mg/kg/hour dose prolonged the APTT to 218 +/- 50% of baseline after 2 minutes and 248 +/- 50% of baseline after 15 minutes. The half-life of the effect on APTT was 40 minutes. The hirulog blood level correlated well with the APTT, prothrombin time and activated clotting time (r = 0.77, 0.73, and 0.82 respectively, all p < 0.001). Both doses of hirulog potently suppressed the generation of fibrinopeptide A (p < 0.05). There were no major hemorrhagic, thrombotic or allergic complications in patients treated with hirulog or heparin. Thus, hirulog, a direct thrombin inhibitor, provides a predictable level of anticoagulation and appears to have a potent yet well-tolerated anticoagulant profile in patients with coronary artery disease.

Reversible late potentials due to ischemia

The role of ischemia in the development of reversible late potentials was assessed in 19 patients undergoing percutaneous transluminal coronary angioplasty. Signal-averaged electrocardiograms were performed before angioplasty, during ischemia caused by balloon inflation and after angioplasty. Five of 19 patients developed late potentials that reverted to normal after angioplasty. Age, sex, ejection fraction, left ventricular end diastolic pressure, vessels involved, and extent of myocardium in jeopardy did not predict the development of late potentials. Patients with a prior history of myocardial infarction were more likely to develop late potentials. Therefore, patients with prior myocardial infarction appear more likely to develop the substrate for reentrant ventricular tachycardia during periods of ischemia.

Prospective Evaluation of Heart Block Complicating Early Lyme Disease

Lyme disease is a recognized cause of heart block/carditis. The incidence of heart block complicating early Lyme disease has not been prospectively evaluated. In this study, 61 patients with early Lyme disease documented by the rash of erythema migrans were prospectively evaluated for carditis. Fifty five of 61 patients had a repeat examination 3 to 4 weeks after initiation of antibiotic therapy. Only one of 61 patients (1.6%) presented with heart block, which resolved with antibiotics. None of the 54 patients without heart block on initial presentation had a change in any measured electrocardiographic parameter or progressed to heart block after antibiotics. Therefore, early Lyme disease appears to be infrequently complicated by heart block. Early administration of antibiotics may prevent the development of heart block/carditis.

Theiler's virus infection induces a specific cytotoxic T lymphocyte response

Theiler's virus, a murine picornavirus, persists in the central nervous system of susceptible mouse strains and causes chronic inflammation and primary demyelination. One of the current hypotheses is that demyelination is, at least in part, mediated by virus-specific cytotoxic T lymphocytes (CTL). However, it is generally assumed that picornaviruses do not induce CTL. In point of fact, their existence has only been demonstrated for Coxsackievirus B-3. To determine whether Theiler's virus induces a CTL response, we generated a murine mastocytoma cell line stably transfected with the coding region of the genome of Theiler's virus strain DA. Using these cells as targets we showed that infected DBA/2 mice, a susceptible strain, produce cytotoxic T lymphocytes. The cytotoxic activity was Theiler's-virus specific. It was for the most part mediated by CD8+ T lymphocytes and H-2 restricted. This is the first demonstration that a specific CTL response is generated during Theiler's virus infection.

Determinants of persistence and demyelination of the DA strain of Theiler's virus are found only in the VP1 gene

The DA strain of Theiler's virus persists in the central nervous systems of mice and causes chronic inflammation and demyelination. The GDVII strain, on the other hand, causes an acute encephalitis that kills the host in a matter of days. We constructed a series of recombinants between two infectious cDNA clones of the genomes of DA and GDVII viruses. Analysis of the phenotypes of the recombinant viruses yielded the following results. (i) Determinants of persistence and demyelination are found only in the VP1 capsid protein of DA virus. (ii) Whereas the VP1 capsid protein of DA virus is able to fully attenuate the neurovirulence of GDVII virus and to allow the chimeric virus to persist and demyelinate, the VP1 capsid protein of GDVII virus is unable to render DA virus neurovirulent. (iii) The mere attenuation of the neurovirulence of GDVII virus does not allow it to persist and demyelinate.

Secondary hypotensive insults in a rat forebrain ischemia model

Previous studies have shown that the recently injured brain has an increased sensitivity to subsequent brief episodes of severe ischemia. This investigation was designed to assess whether less severe secondary insults, which alone would be incapable of producing injury, exacerbate brain damage resulting from a primary episode of global ischemia. Rats were subjected to either 10 min of 2-vessel forebrain ischemia (primary insult alone), 20 min of hypotension (mean arterial pressure, MAP = either 40 or 25 mmHg) without vessel occlusion (secondary insult alone), or 10 min ischemia followed 1 h later by the hypotensive challenge (primary + secondary insult). Seven days later, the animals were neurologically evaluated and the brains then prepared for histologic analysis. Neither magnitude of secondary insult alone was found to produce injury. In contrast, the primary insult alone caused moderate damage in the hippocampus, caudoputamen and neocortex. With the exception of increased neuronal necrosis in the hippocampal CA1 sector in rats receiving the primary + secondary insult (MAP = 25 mmHg), no worsening of outcome could be attributed to the secondary insults. These results indicate that the recovering brain may not be as sensitive to hypoperfusion as has previously been suggested.

Acute reversible diffuse conduction system disease due to Lyme disease

During the acute phase of Lyme disease, a 56-year-old man without previous heart disease developed complete heart block with alternating left and right bundle branch block pattern QRS complexes. Electrophysiological study performed in the acute phase revealed marked HV prolongation, although the level of heart block was at the atrioventricular node. The heart block was mildly symptomatic and resolved (as did the bundle branch block) with antibiotic therapy. Lyme disease may cause reversible His-Purkinje disease.

Nitrous oxide does not alter infarct volume in rats undergoing reversible middle cerebral artery occlusion

This experiment was designed to determine if nitrous oxide alters neurologic and pathologic outcome from temporary focal cerebral ischemia in spontaneously hypertensive rats deeply anesthetized with a barbiturate. Two groups of rats were given intravenous methohexital such that a stable EEG pattern of burst suppression was achieved. In one group of rats (n = 11), the lungs were mechanically ventilated with 70% N2O/30% O2, and in the other group (n = 10), ventilation was done with 70% nitrogen/30% O2. The middle cerebral artery was then occluded for 2 h, during which time mean arterial pressure, blood gases, hematocrit, plasma glucose, and head temperature were held constant between groups. The total doses of methohexital administered were similar in both groups as were the plasma methohexital concentrations immediately prior to onset of ischemia. After reperfusion of the middle cerebral artery, the animals were allowed to awaken. Neurologic evaluations were performed prior to ischemia and at 24 and 96 h postischemia. Cerebral infarct volume was measured at 96 h postischemia using triphenyl tetrazolium chloride staining and computer imaging techniques. There were no neurologic differences between the N2O and nitrogen groups at any experimental interval although both groups exhibited deficits at both 24 and 96 h postischemia relative to preischemic values. The two groups also had nearly identical cerebral infarct volumes (N2O = 231 +/- 97 mm3; nitrogen = 226 +/- 75 mm3; mean +/- SD).(ABSTRACT TRUNCATED AT 250 WORDS)