Correlation between GABA(A) receptor density and vagus nerve stimulation in individuals with drug-resistant partial epilepsy

Vagus nerve stimulation (VNS) is an important option for the treatment of drug-resistant epilepsy. Through delivery of a battery-supplied intermittent current, VNS protects against seizure development in a manner that correlates experimentally with electrophysiological modifications. However, the mechanism by which VNS inhibits seizures in humans remains unclear. The impairment of gamma-aminobutyric acid (GABA)-mediated neuronal inhibition associated with epilepsy has suggested that GABA(A) receptors might contribute to the therapeutic efficacy of VNS. We have now applied single photon emission computed tomography (SPECT) with the benzodiazepine receptor inverse agonist [123I]iomazenil to examine cortical GABA(A) receptor density (GRD) before and 1 year after implantation of a VNS device in 10 subjects with drug-resistant partial epilepsy. VNS therapeutic responses resulted significantly correlated with the normalization of GRD. Moreover, a comparable control group, scheduled for a possible VNS implant, failed to show significant GRD variations after 1 year of a stable anti-epileptic treatment. These results suggest that VNS may modulate the cortical excitability of brain areas associated with epileptogenesis and that GABA(A) receptor plasticity contributes to this effect.

Diagnostic value of nystagmus: spontaneous and induced ocular oscillations

Research over the past 20 years has provided a clearer understanding of the pathogenesis of most forms of nystagmus and other ocular oscillations. To the clinician, these advances translate into greater accuracy of nystagmus as a diagnostic sign. However, to capitalise on these advances, it is important to systematically examine eye movements and interpret the findings with reference to pathophysiology. In this review we describe a scheme for examining the patient with nystagmus and interpreting common ocular oscillations; some examples are provided as video clips.

Quantitative assessment of WT1 expression by real time quantitative PCR may be a useful tool for monitoring minimal residual disease in acute leukemia patients

In order to verify if quantitative assessment of the WT1 transcript amount by the real time quantitative PCR (RQ-PCR) can be used as a marker for minimal residual disease detection, the WT1 transcript amount was determined in BM and PB samples of patients with myeloid and lymphoid acute leukemia, in normal controls, in regenerating bone marrow samples and in purified CD34-positive cells from normal subjects. In 10 patients bearing a fusion gene transcript suitable for minimal residual disease quantitative assessment, we performed a simultaneous analysis of the WT1 and of the fusion-gene transcript at sequential time intervals during follow-up. Sequential WT1 analysis was also performed in five AML patients lacking additional molecular markers. The data obtained show that normal and regenerating BM samples and purified CD34-positive cells consistently express minimal amounts of WT1 transcript and that this is extremely low and frequently undetectable in normal PB. By contrast, high levels of WT1 expression are present in the BM and PB samples of all acute leukemia (AL) cases at diagnosis. The WT1 levels during follow-up were found to follow the pattern of the other molecular markers (fusion gene transcripts) used for MRD monitoring and increased WT1expression in the BM and/or PB during follow-up of AL patients was always found to be predictive of an impending hematological relapse.

Serotonin and serotonin receptor expression in the aorta of carotid intact and denervated newborns

Pharmacological blocking of serotonin (5-HT) 5A receptors abolishes aortic ventilatory chemosensitivity of carotid body denervated (CBD) piglets [J. Appl. Physiol. 92 (2002) 893]. Accordingly, the purpose of the present study was to determine whether 5-HT and 5-HT receptors exist at aortic sites that are chemosensitive after CBD. Aortas from CBD and sham CBD rats and piglets and from aortic denervated (AOD) and combined AOD+CBD piglets were harvested, sectioned and then studied using immunohistochemistry and western blot techniques. 5-HT immunoreactivity in piglets and rats was concentrated in the endothelium and sub-endothelial areas in several aortic regions studied, and in some areas also in the adventitia. At the aortic chemosensitive site (descending aorta in CBD piglets and the ascending aorta in CBD rats), the immunoreactivity was greater (P < 0.05) than in other aortic regions and greater than in other groups studied. The 5-HT(5a) receptor was expressed only at the chemosensitive sites and only in aortic innervated piglets. We conclude that the data from this and a previous study [J. Appl. Physiol. 92 (2002) 893] suggest that a serotonergic mechanism contributes to the aortic ventilatory chemoreflex after CBD.

Assessment of minimal residual disease (MRD) in CBFbeta/MYH11-positive acute myeloid leukemias by qualitative and quantitative RT-PCR amplification of fusion transcripts

The inv(16)(p13q22) chromosomal rearrangement associated with FAB M4Eo acute myeloid leukemia (AML) subtype is characterized by the presence of the CBFbeta/MYH11 fusion transcript that can be used to detect minimal residual disease (MRD). However, qualitative RT-PCR studies of MRD have so far produced conflicting results and seem of limited prognostic value. We have evaluated retrospectively MRD in a large series of CBFbeta/MYH11-positive patients employing both qualitative and quantitative (real-time PCR) approaches. 186 bone marrow samples from 36 patients were examined with a median follow-up of 27.5 months; 15 patients relapsed during follow-up. In qualitative studies, carried out by 'nested' RT-PCR assay, all patients in complete remission (CR) immediately after induction/consolidation therapy were found to be PCR positive. However, follow-up samples at later time points were persistently negative (except one case) in patients remaining in continuous CR (CCR) for more than 12 months. 16 patients were evaluated by quantitative real-time PCR assay: CBFbeta/MYH11 transcript copy number was normalized for expression of the housekeeping gene ABL, expressed as fusion gene copy number per 10(4) copies of ABL. A 2-3 log decline in leukemic transcript copy number was observed after induction/consolidation therapy. After achieving CR, the mean copy number was significantly higher in patients destined to relapse compared to patients remaining in CCR (151 vs 9, P < 0.0001 by Mann-Whitney test). Moreover, in CCR patients, the copy number dropped below the detection threshold after the treatment protocol was completed and remained undetectable in subsequent MRD analysis in accordance with results obtained by qualitative RT-PCR. On the contrary, in the seven patients who relapsed, the copy number in CR never declined below the detection threshold; thus a cut-off value discriminating these two groups of patients could be established. The findings of our study, if confirmed, might confer an important predictive value to quantitative real-time PCR determinations of MRD in patients with inv(16) leukemia.

[Neonatal vocal cord palsy. Clinical and therapeutical approaches]

Between 1998 and 2000, four newborns have been observed for laryngeal stridor occurred some hours after birth. Otorhinolaryngologic examinations, as well as cardiac, neuroradiologic and serologic investigations have been performed to formulate the diagnosis and verify the etiology. The fiberoptic laryngoscopy showed a bilateral paralysis of the vocal cord in two newborns, a monolateral paralysis of the left vocal cord in another and in the last one, instead, a bilateral cordal hypomobility. The follow-up performed till the age of one year showed a complete remission of the symptomatology in two newborns, respectively in the one with monolateral paralysis and in the other affected by hypomobility of the vocal cords; of the two newborns with bilateral paralysis, instead, one is dead because of Haemophilus Influenzae epiglottitis, three weeks after discharge without physicians' consensus, while in the other patient, affected by lobar holoprosencephaly, it was necessary to perform a tracheotomy because of a severe obstructive apnea. The lobar holoprosencephaly, is a cerebral malformation characterized by the partial separation of the cerebral hemispheres, and it is described for the first time associated with bilateral vocal cords paralysis.

Effects of carotid and aortic chemoreceptor denervation in newborn piglets

The objective of the present study was to test the hypothesis that in neonatal piglets there would be no hypoventilation after sham denervation or aortic denervation (AOD) alone, but there would be transient hypoventilation after carotid body denervation (CBD) and the hypoventilation would be greatest after combined carotid and aortic denervation (CBD+AOD). There was a significant (P < 0.05) hypoventilation in CBD and CBD+AOD piglets denervated at 5, 15, and 25 days of age. The hypoventilation in CBD+AOD piglets denervated at 5 days of age was greater (P < 0.05) than that of all other groups. Conversely, sham-denervated and AOD piglets did not hypoventilate after denervation. Injections of sodium cyanide showed that aortic chemoreceptors were a site of recovery of peripheral chemosensitivity after CBD. This aortic sodium cyanide response was abolished by prior injection of a serotonin 5a receptor blocker. Residual peripheral chemosensitivity after CBD+AOD was localized to the left ventricle. We conclude that 1) aortic chemoreceptors contribute to eupneic breathing in piglets that were carotid denervated at 5 days of age and 2) there are multiple sites of residual peripheral chemosensitivity after CBD.

Non-invasive proportional assist and pressure support ventilation in patients with cystic fibrosis and chronic respiratory failure

BACKGROUND

Patients with advanced cystic fibrosis can benefit from non-invasive positive pressure ventilation (NPPV) for the treatment of acute decompensation as well as for the management of chronic respiratory failure. This study was undertaken to compare the physiological effects of non-invasive proportional assist ventilation (PAV) and pressure support ventilation (PSV) on ventilatory pattern, transcutaneous blood gas tensions, and diaphragmatic effort in stable patients with cystic fibrosis and chronic CO2 retention.

METHODS

In 12 patients two periods of spontaneous breathing were followed randomly by PSV (12 (3) cm H2O) and PAV (flow assist 4.9 (1.3) cm H2O/l.s, volume assist 18.9 (5.1) cm H2O/l) set for the patient's comfort and administered for 40 minutes with 2 cm H2O continuous positive airway pressure. Ventilatory pattern, transcutaneous blood gas tensions, and surface diaphragmatic electromyography were measured in the last 10 minutes of each application.

RESULTS

On average, both PSV and PAV improved ventilation (+30%), tidal volume (+30%), and transcutaneous CO2 (-7%) while reducing diaphragmatic activity (-30% with PSV, -20% with PAV). Mean inspiratory airway pressure was lower during PAV than during PSV (9.7 (1.9) and 12.9 (2.7) cm H2O, respectively; p<0.05). The mean coefficient of variation of tidal volume was about 20% (range 11-39%) during spontaneous breathing and did not change with either PAV or PSV.

CONCLUSIONS

These results show that short term administration of nasal PAV and PSV to patients with stable cystic fibrosis with chronic respiratory insufficiency is well tolerated, improves ventilation and blood gas tensions, and unloads the diaphragm.

Prophylactic hemodialysis after radiocontrast media in patients with renal insufficiency is potentially harmful

PURPOSE

Acute renal failure induced by contrast media is an important cause of hospital-acquired renal insufficiency. Preexisting renal failure and the dose of contrast media are known risk factors for the development of radiocontrast nephropathy. We performed a randomized trial to test whether radiocontrast nephropathy can be avoided by prophylactic hemodialysis immediately after the administration of contrast media in patients with impaired renal function.

SUBJECTS AND METHODS

Renal function and other parameters, hemodialysis requirement, and relevant clinical events were recorded before and during the 6 days after administration of contrast media in 113 patients with a baseline serum creatinine level >200 microm/L (>2.3 mg/dL). Patients were randomly assigned to either hemodialysis (n = 55) or nonhemodialysis (n = 58) treatment after parenteral low-osmolality contrast media.

RESULTS

The characteristics of the patients in the two groups were similar. Compared with baseline levels, the mean [+/- SD] serum creatinine level decreased at day 1 (277 +/- 95 microm/L), peaked at day 4 (353 +/- 126 microm/L), and returned to baseline at day 6 (327 +/- 119 microm/L, P <0.05 by analysis of variance) after administration of contrast media in the hemodialysis group, whereas in the nonhemodialysis group, no significant changes in mean serum creatinine level were observed. Eleven patients required 1 or more hemodialyses (8 in the hemodialysis group and 3 in the nonhemodialysis group, P = 0.12), 6 of whom (4 vs. 2, P = 0.44) required 3 or more hemodialyses. Clinically relevant events included pulmonary edema (1 vs. 4 patients, P = 0.36), myocardial infarction (2 vs. 2), stroke (2 vs. 0, P = 0.24), and death (1 vs. 1).

CONCLUSIONS

The strategy of performing hemodialysis immediately after the administration of low-osmolality contrast media in all patients with a reduced renal function did not diminish the rate of complications, including radiocontrast nephropathy.

Holoprosencephaly (lobar form) associated with bilateral vocal cord palsy

There have been many causes associated with bilateral vocal cord palsy, both congenital and perinatal. Until now, the main congenital causes of bilateral vocal cord palsy have been associated with meningomyelocele, Arnold-Chiari malformation, and hydrocephalus. We report a patient with bilateral vocal cord palsy associated with the lobar form of holoprosencephaly. In this case, bilateral vocal cord palsy was caused by the disruption of the cortical laryngeal motoneurons. Neonatal stridor must be carefully evaluated by the neonatologist to exclude severe cerebral anomalies.

A prospective study evidencing rhinomanometric and olfactometric outcomes in women taking oral contraceptives

BACKGROUND

The aim of this prospective study was to evaluate the changes in olfactory sensitivity of oral contraceptive (pill) users.

METHODS

Sixty women underwent rhinomanometric and olfactometric determinations during the follicular, periovular and luteal phases of the menstrual cycle, and at day 7, 14 and 21 of contraceptive intake. Thirty-one women used 30 microg ethinyl oestradiol plus 75 microg gestodene and 29 women used 20 microg ethinyl oestradiol plus 150 microg desogestrel.

RESULTS

Rhinomanometry showed higher but not statistically significant values during the periovular phase than in the follicular and luteal phases. Olfactometry showed a higher sensitivity during the follicular and periovular phases than during the luteal phase of the menstrual cycle. The rhinomanometric surveys in pill users were statistically different from those of the luteal phase (P < 0.02) and the follicular and periovular phases (P < 0.001). The olfactometric thresholds during the period of contraceptive use were statistically different from those of the follicular phase for a few odorous substances, and from those of the periovular phase for each odorous substance, but similar to those of the luteal phase (P = NS).

CONCLUSIONS

Unlike the rhinomanometric airflow and trans-nasal pressure, the olfactory threshold to odours seems to depend on the variations of the ovarian steroids during the menstrual cycle and on the iatrogenic effects of oral contraceptives.

PECAM-1/IgG attenuates peroxynitrite-mediated extremity reperfusion injury

OBJECTIVE

Neutrophil transendothelial migration, a key feature of skeletal muscle ischemia and reperfusion (I/R) injury, is mediated by the platelet endothelial cell adhesion molecule-1 (PECAM-1). Peroxynitrite anion, a toxic product of neutrophil superoxide anion and nitric oxide, contributes to oxidative skeletal muscle injury and can be quantified by measurement of protein tyrosine nitration after I/R. This study hypothesizes that administration of the PECAM-1/IgG antibody chimera will inhibit peroxynitrite-mediated injury after I/R.

METHODS

The study was composed of five groups: an I/R group (n = 4), a sham treatment group anesthetic control (n = 3), a treatment group receiving the PECAM-1/immunoglobulin G (IgG) antibody chimera with I/R (n = 9), a treatment group receiving human IgG with I/R as an antibody control (n = 6), and a treatment group receiving normal saline solution with I/R as a vehicle control (n = 5). The right hind limb in male New Zealand white rabbits was rendered ischemic by occluding the iliac and femoral arteries for 3 hours, followed by 2 hours of reperfusion (I/R). Sham-treated rabbits underwent arterial dissection without arterial occlusion. PECAM-1/IgG-treated rabbits and IgG-treated rabbits received an infusion of 1 mg/kg in normal saline solution 20 mL via an ear vein catheter during the last 5 minutes of ischemia and the first 15 minutes of reperfusion. Saline solution-treated rabbits similarly received normal saline solution 20 mL. The anterior tibialis muscle was harvested after reperfusion. Immunohistochemical staining for nitrotyrosine was performed with monoclonal antinitrotyrosine antibodies and fluorescently labeled secondary antibodies. Computed morphometric study was performed to calculate relative fluorescence scores for each histologic section. Averaged fluorescence scores were analyzed by one-way analysis of variance with Bonferroni post hoc comparison.

RESULTS

The averaged fluorescence scores (mean +/- SEM) for the sham-treated (2.88 +/- 0.78) and PECAM-1/IgG-treated (6.16 +/- 0.43) groups demonstrated a significant reduction in quantitative fluorescence compared with the IgG- (15.17 +/- 2.01) and saline solution-treated (17.46 +/- 3.71) control groups, and the I/R-treated (18.52 +/- 3.00) group, (P <.05).

CONCLUSIONS

These results suggest that PECAM-1/IgG diminishes peroxynitrite-mediated oxidative skeletal muscle injury by inhibiting neutrophil transendothelial migration and may therefore prove a useful therapeutic agent in the treatment of reperfusion injury.

Mortality after carotid body denervation in rats

Carotid body denervation (CBD) in neonatal goats and piglets results in minimal irregular breathing and no fatalities. Redundancy and/or plasticity of peripheral chemosensitivity and a relatively mature ventilatory control system at birth may contribute to the paucity of CBD effects in these species. In the present study, we tested the hypothesis that CBD mortality would be greater in neonates of a less mature species such as the rat. We found that the mortality in rats denervated at 2-3 and 7-8 days of age was significantly higher (P < 0.05) than in sham-CBD rats. In all surviving rats, pulmonary ventilation during hypoxia was lower in CBD than in sham operated rats 2 days after denervation. In surviving rats denervated during the 7th and 8th postnatal days, there was also reduced weight gain and pulmonary ventilation during eupnea, including apneas up to 20 s in duration. However, the effects of CBD were compensated within 3 wk after denervation. Local injections of NaCN indicated that aortic chemoreceptors might have been one of the sites of recovery of peripheral chemosensitivity. We concluded that CBD has higher mortality in newborn rats than in other mammals, possibly because of the relative immaturity of these animals at birth. Nonetheless, in survivors there was enough redundancy and plasticity in the control of breathing to eventually compensate for the consequences of CBD.

[Canaud central venous catheters: 4-year experience]

BACKGROUND

The use of central venous catheters for permanent vascular access has become increasingly important because of the characteristics and the clinical problems of incident patients or patients already undergoing chronic hemodialysis. In this study a short and medium term evaluation was made of a double permanent central venous catheter positioned in the right internal jugular vein. The Canaud catheter was evaluated both from the point of view of practical use and for various technical and clinical problems.

METHODS

During the observation period, July 1995 - September 1999, these catheters were used in 39 patients (mean age 72 years), 22 females and 17 males; 31% were diabetic patients and 46% were older than 75 years. Forty-five catheters were positioned with an average dwelltime of 347 days.

RESULTS

Utilization was almost immediate and the resulting blood flow was suitable for all depurative techniques (blood flow more than 250 ml/min), with an average recirculation of 11.9% and an average resistance index of 0.54. Among the most serious complications during surgery a respiratory block was observed followed by the complete recovery of the patient. Some clinical complications were noted (5 venous thrombosis), as were some technical ones: 12% well as related to problems with the adapter, 24.3% to reversible thrombosis of the catheters occurred in 23 catheters in 22 patients. Infections.

CONCLUSIONS

Overall Canaud catheters appear to represent a valid alternative to other more recent catheters for permanent vascular access. If necessary, they can be easily substituted due to the absence of a subcutaneous cuff.

Tonometry after laser in situ keratomileusis treatment

PURPOSE

To assess the reliability of intraocular pressure measurements by Goldmann applanation tonometry versus pneumotonometry after laser in situ keratomileusis for myopia.

PATIENTS AND METHODS

In this prospective study, corneal Goldmann applanation tonometry and pneumotonometry measurements were made in 118 eyes of 60 patients before and 1 and 3 months after undergoing laser in situ keratomileusis for myopia. Manifest refraction, ultrasonic corneal thickness measurements, and keratometry readings were also obtained.

RESULTS

Preoperative intraocular pressure showed a good correlation between Goldmann applanation tonometry and pneumotonometry values (Pearson r = 0.71; P < 0.001). although Goldmann applanation tonometry readings were slightly higher at low intraocular pressure values and slightly lower at high intraocular pressure values. After a mean stromal ablation depth of 77.1 microm, mean intraocular pressure by Goldmann applanation tonometry decreased significantly (P < 0.001) from a preoperative value of 14.8 +/- 11.9 mm Hg to 11.9 +/- 2.1 mm Hg and 11.7 +/- 1.7 mm Hg after 1 and 3 months, respectively. Mean pre- and post-laser in situ keratomileusis measurements by pneumotonometry were similar (P = 0.8). Differences of postoperative intraocular pressure measurements by Goldmann applanation tonometry and pneumotonometry were statistically significant. After 3 months, there was a poor correlation between Goldmann applanation tonometry and pneumotonometry intraocular pressure values (Pearson r = 0.58). Postoperative intraocular pressure decrease in applanation tonometry correlated with changes in keratometry, spherical equivalent, and central corneal thickness. Regression analysis showed a decrease of 2.9 mm Hg per 70 microm reduction in central corneal thickness.

CONCLUSIONS

Contact pneumotonometry measures the IOP reliably after laser in situ keratomileusis for myopia, whereas Goldmann applanation tonometry underestimates the intraocular pressure. This may be important in the treatment of any future glaucoma.