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Biomedical subjects

B Clair

Publications and source records attributed to B Clair.

At least 19 recordsLinked to original sources
PubMed2005

Significance of phrenic nerve electrophysiological abnormalities in Guillain-Barré syndrome.

The authors investigated whether the amplitude and latency of diaphragm compound muscle action potential helped predict respiratory failure in Guillain-Barré syndrome. Both variables were significantly but weakly correlated with vital capacity (VC) and were similar in unventilated (n = 60) and ventilated (n = 10) patients. In ventilated patients, motor loss severity, progression, and VC reduction were significantly greater, and bulbar dysfunction was more common. Predicting respiratory failure must rely on clinical features and VC.

Action Potentials↗
PubMed2005

The influence of uridine diphosphate glucuronosyl transferase 1A promoter polymorphisms, beta-globin gene haplotype, co-inherited alpha-thalassemia trait and Hb F on steady-state serum bilirubin levels in sickle cell anemia.

PURPOSE: Homozygosity for the (AT)7 allele of uridine diphosphate glucuronosyl transferase 1A (UGT1A1) gene polymorphism is associated with increased bilirubin levels in sickle cell anemia (SCA). In the present study, in addition to UGT1A1 promoter genotype, serum bilirubin level was related to other genetic modifiers -beta(S)-globin gene haplotype, Hb F, co-inherited alpha-thal trait, age and gender. METHODS: The patients were randomly selected from the sickle cell clinic, Medical College of Georgia. UGT1A1 promoter polymorphisms were determined using automated sequencing. Other investigations were with standard techniques. RESULTS: There were 67 SCA patients (41 males and 26 females), aged 2-44 yr (mean of 20.6 +/- 10.7). Ten (14.9%) patients were homozygous for the (AT)6 UGT1A1 allele, 35 (52.2%) were heterozygous for (AT)6 and (AT)7 alleles while 22 (32.8%) were homozygous for (AT)7. Serum bilirubin was significantly higher in the homozygous (AT)7 group (3.7 +/- 1.5, 3.8 +/- 2.3 and 5.6 +/- 2.4 mg/dL, respectively). It was also significantly higher in males than females and in patients aged >10 yr. There was a significant negative linear correlation (r = -0.304, P = 0.016) of serum bilirubin with Hb F. The beta-globin haplotype and co-existing alpha-thal trait did not have any significant influence on serum bilirubin levels. Patients on hydroxyurea were older, had lower Hb F, but higher mean serum bilirubin. The latter also was signifcantly higher among those with UGT1A1 (AT)7 homozygosity. CONCLUSIONS: Apart from UGT1A1 (AT)7 homozygosity, Hb F, age and gender are the other factors that significantly influence serum bilirubin level in SCA.

Adolescent↗
PubMed2001

Supine fall in lung volumes in the assessment of diaphragmatic weakness in neuromuscular disorders.

OBJECTIVE: To determine whether diaphragmatic function can be determined by noninvasive respiratory indices in neuromuscular disease. DESIGN: Vital capacity (VC) and mouth pressure generated during a maximal static inspiratory effort (Pi max) were measured with patients in both sitting and supine positions. SETTING: Rehabilitation hospital. PATIENTS: Twenty-four patients with generalized neuromuscular disease. MAIN OUTCOME MEASURES: Changes in indices from sitting to supine position were compared with invasive diaphragmatic function indices consisting of transdiaphragmatic pressures during maximal sniff (Pdi sniff) and the ratio of gastric pressure (Pga) increases over transdiaphragmatic pressure (DeltaPga/DeltaPdi) during quiet breathing. RESULTS: The fall in VC in the supine position was greater in the 15 patients who had spontaneous paradoxical diaphragmatic motion (DeltaPga/DeltaPdi < 0) than in the 9 patients who did not. Specificity and sensitivity of a greater than 25% supine fall in VC for the diagnosis of diaphragmatic weakness (DeltaPga/DeltaPdi < 0 and/or Pdi sniff < 30cmH2O) were 90% and 79%, respectively. Stepwise multiple regression analysis of Pdi sniff showed that both the supine fall in VC and Pi max were associated with diaphragmatic weakness (R(2) =.66; p <.0001). These factors contributed 52% and 14% of the Pdi sniff variance, respectively. CONCLUSIONS: Simple VC measurement in the sitting and supine positions may be helpful in detecting severe or predominant diaphragmatic weakness.

Adult↗
PubMed2000

[Corticotherapy in severe infectious states].

Septic shock is one of the leading cause of death in modern countries. Scientists have made huge improvement in the understanding of mechanisms of inflammation, and the sequence of activation of the various pro and anti-inflammatory markers is now well known. By contrary, physicians have failed to improve survival from septic shock, in spite of the development of specific targets of the various points of the cytokine cascade sought to have a key role in host survival to sepsis. Corticosteroids were among the first anti-inflammatory drugs, which have been tested in high quality randomised controlled trials. These trials clearly showed that patients with septic shock are unlikely to benefit from a short course of a large dose of an anti-inflammatory steroid. More recent findings highlighting the role of the integrity of the hypothalamic-pituitary -adrenal axis to appropriately respond to a septic insult, have led to a reappraisal of the use of steroids in septic shock. Several high quality randomised controlled trials have evaluated the efficacy and safety of a prolonged treatment with low dose hydrocortisone in severe sepsis. These trials strongly suggested that this strategy of corticotherapy reduced the morbidity of septic shock and may favourably affect survival from septic shock.

Adrenal Cortex Hormones↗
PubMed1999

Mechanisms underlying effects of nocturnal ventilation on daytime blood gases in neuromuscular diseases.

The hypothesis that, in neuromuscular and chest wall diseases, improvement in central respiratory drive explains the effects of night-time ventilation on diurnal gas exchanges was tested. The effects at 6 months, 1, 2 and 3 yrs of intermittent positive pressure ventilation (IPPV) on arterial blood gas tension, pulmonary function, muscle strength, sleep parameters, respiratory parameters during sleep and ventilatory response to CO2 were evaluated in 16 consecutive patients with neuromuscular or chest wall disorders. As compared with baseline, after IPPV daytime arterial oxygen tension (Pa,O2) increased (+2.3 kPa at peak effect) and arterial carbon dioxide tension (Pa,CO2) and total bicarbonate decreased (-1.8 kPa and -5 mmol x L(-1), respectively) significantly; vital capacity, total lung capacity, maximal inspiratory and expiratory pressures and alveolar-arterial oxygen gradient did not change; the apnoea-hypo-opnoea index and the time spent with an arterial oxygen saturation (Sa,O2) value <90% decreased (-24 and -101 min, respectively), sleep efficiency and mean Sa,O2 increased (+16% and +5%, respectively); and ventilatory response to CO2 increased (+4.56 L x min(-1) x kPa(-1)) significantly. The reduction in Pa,CO2 observed after IPPV correlated solely with the increase in the slope of ventilatory response to the CO2 curve (r=-0.68, p=0.008). In neuromuscular or chest wall diseases, improvement of daytime hypoventilation with nocturnal intermittent positive pressure ventilation may represent an adaptation of the central chemoreceptors to the reduction of profound hypercapnia during sleep or reflect change in the quality of sleep.

Adult↗
PubMed1998

Circulating transforming growth factor beta 1 (TGF-beta1) in Guillain-Barré syndrome: decreased concentrations in the early course and increase with motor function.

OBJECTIVE: To delineate the possible implication of the immunosuppressive cytokine transforming growth factor beta 1 (TGF-beta1) in the pathogenesis of Guillain-Barré syndrome. Guillain-Barré syndrome is a disorder that may implicate cytokines in its pathogenesis. TGF-beta1 is a potent anti-inflammatory cytokine occasionally shown to be regulated in the course of demyelinating disorders. METHODS: The study measured circulating proinflammatory and anti-inflammatory cytokines from the progressing phase to early recovery in patients with Guillain-Barré syndrome. Plasma concentrations of TNF-alpha, IL-beta1, IL-2, IL-4, IL-6, IL-10, and TGF-beta1 were prospectively evaluated in 15 patients with Guillain-Barré syndrome every three days for the first 15 days after admission to hospital, and in 15 controls with non-inflammatory neurological diseases. RESULTS: Concentrations of TGF-beta1 in plasma were decreased in 13115 patients (87 %) at day 1, remained low during progression and the plateau of paralysis (days 1-10), and then progressively increased up to control concentrations during early recovery (days 12-15). Concentrations of plasma TGF-beta1 correlated positively with motor function, the lowest values being e found in the most disabled patients. Concentrations of plasma TGF-beta1 were decreased before any treatment, and during treatment by either plasma exchange or intravenous immunoglobulins, plasma exchange being associated with a more pronounced decrease in TGF-beta1 at day 7. Circulating TNF-alpha concentrations were raised, as previously reported, when other cytokines were either randomly increased (IL-2, IL-6), or undetectable (IL-1, IL-4, IL-7, IL-10). CONCLUSIONS: Down regulation of TGF-beta1 in the early course of Guillain-Barré syndrome could participate in neural inflammation.

Adjuvants, Immunologic↗
PubMed1998

[Long-term ventilation at home in adults with neurological diseases].

Respiratory handicap due to neurological diseases is often underestimated. Given clinical signs are either mild or absent, systematic measurement of the vital capacity is the best mean to detect in practice the restrictive syndrome. The onset of home mechanical ventilatory support should be decided at steady state, apart from episodes of acute respiratory failure. Two types of indications should be distinguished. Necessary ventilation aims at supplying over day and night the respiratory insufficiency incurred by the paralysis of respiratory muscles. Although the criteria for the use of such a supply differ according to the neurological disease, a daytime hypercapnia above 45 mmHg is widely accepted in the literature. It is otherwise established to use first a non invasive technique, while tracheostomy is secondarily proposed in case of failure of these techniques. The application of this therapeutic strategy in Duchenne de Boulogne muscular dystrophy showed that, given that tracheostomy will become necessary in this evolutive disease, proposal of an early tracheostomy is not nonsensical. By contrast, preventive ventilation aims at preventing from the aggravation of the restrictive syndrome in those patients with no criterion for necessary ventilation. It has been proved ineffective in Duchenne muscular dystrophy through a controlled clinical trial.

Adult↗
PubMed1997

Peripheral neuropathy in human immunodeficiency virus-infected patients with the diffuse infiltrative lymphocytosis syndrome.

A subset of human immunodeficiency virus (HIV)-infected patients develop persistent CD8 hyperlymphocytosis and a Sjogren's syndrome-like syndrome associated with multivisceral CD8 T-cell infiltration, known as the diffuse infiltrative lymphocytosis syndrome (DILS). Patients with DILS tend to have higher CD4 cell counts, fewer opportunistic infections, and longer survival times than other HIV-infected patients. Peripheral nerve involvement in DILS has been poorly documented. We studied 12 HIV-infected patients with CD8 hyperlymphocytosis, DILS, and clinical signs of peripheral neuropathy. Two of 4 patients who were HLA typed were HLA-DR5 and 1 was HLA-DR6. All patients had the sicca syndrome and multivisceral involvement. The neuropathy was acute or subacute, always painful, and symmetrical in 8 cases. Electrophysiology was consistent with axonal neuropathy in 10 of 12 patients. Nerve biopsy showed marked angiocentric CD8 infiltrates without mural necrosis (12 of 12), and abundant expression of HIV p24 protein in macrophages (12 of 12). The HIV genome was detected by polymerase chain reaction in nerve homogenates. Zidovudine therapy was associated with improvement in 6 of 6 patients and steroid therapy was beneficial in 4 of 5 patients. No T-cell lymphoma was observed during follow-up, but 2 patients developed a primary B-cell lymphoma. We conclude that DILS neuropathy represents HIV-associated neuropathy, characterized by marked CD8 infiltration and abundant HIV in nerve, that improves with zidovudine or steroid therapy, and probably reflects a systemic host-determined and antigen-driven response to HIV.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Clinical trial of plasma exchange and high-dose intravenous immunoglobulin in myasthenia gravis. Myasthenia Gravis Clinical Study Group.

We have conducted a trial to randomly assess the efficacy and tolerance of intravenous immunoglobulin (i.v.Ig) or plasma exchange (PE) in myasthenia gravis (MG) exacerbation and to compare two doses of i.v.Ig. Eighty-seven patients with MG exacerbation were randomized to receive either three PE (n = 41), or i.v.Ig (n = 46) 0.4 gm/kg daily further allocated to 3 (n = 23) or 5 days (n = 23). The main end point was the variation of a myasthenic muscular score (MSS) between randomization and day 15. The MSS variation was similar in both groups (median value, +18 in the PE group and +15.5 in the i.v.Ig group, p = 0.65). Similar efficacy, although slightly reduced in the 5-day group was observed with both i.v.Ig schedules. The tolerance of i.v.Ig was better than that of PE with a total of 14 side effects observed in 9 patients, 8 in the PE group and 1 in the i.v.Ig group (p = 0.01). Although our trial failed to show a pronounced difference in the efficacy of both treatments, it exhibited a very limited risk for i.v.Ig. i.v.Ig is an alternative for the treatment of myasthenic crisis. The small sample sizes in our trial, however, could explain why a difference in efficacy was not observed. Further studies are needed to compare PE with i.v.Ig and to determine the optimal dosage of i.v.Ig.

Adult↗
PubMed1996

Circulating tumor necrosis factor (TNF)-alpha and soluble TNF-alpha receptors in patients with Guillain-Barré syndrome.

Guillain-Barré syndrome (GBS) is an inflammatory disorder that may implicate proinflammatory cytokines such as TNF-alpha in its pathogenesis. We determined serum levels of TNF-alpha and the specific antagonists sTNF-Rs p55 and p75 in 24 patients with GBS at days 1, 15 and 30 of hospitalization. Patients were in the progression phase of the disease at day 1, and in the recovery phase at day 30. They were classified as able to walk (stage A), confined to bed (B), or under assisted ventilation (C). All patients underwent plasma exchange within day 1-12. At day 1, TNF-alpha levels were elevated in 15/24 patients, and sTNF-Rs were elevated in 21/23. TNF-alpha levels had not decreased at day 15, and dropped at day 30 (p < 0.04), whereas sTNF-R p55 remained elevated at day 15 and day 30. The TNF-alpha/sTNF-Rs ratio, estimating active TNF-alpha unbound to sTNF-Rs, decreased from day 1 to day 30 (p < 0.05). A positive correlation was found between disease severity and sTNF-R serum levels (p < 0.01). In conclusion, elevated circulating sTNF-Rs assesses activation of the TNF-alpha system in almost all patients with GBS and correlates positively with disease severity. Drop of TNF-alpha contrasting with sustained elevation of sTNF-R p55 during recovery suggests that sTNF-R p55 may be important in the fading of the neural inflammatory effect of TNF-alpha in GBS.

Antibody Specificity↗
PubMed1996

Immunoglobulin A levels in bronchial samples during mechanical ventilation and onset of nosocomial pneumonia in critically ill patients.

Local immunoglobulins play a key role in host defense against lung infection. We investigated the pattern of evolution of bronchial albumin, IgA, and IgG levels in ventilated ICU patients in relation to nosocomial pneumonia. Immunocompetent, critically ill patients underwent serial blood and bronchial protein determinations on Day 1 (intubation day), and on Days 3, 7, 10, and 14. The variations in proteins levels were compared with corresponding Day 1 values in the whole population, and between patients who developed lung infections (Group A) and the remaining population (Group B). Forty-four patients were included into the study. In the whole population, when compared with the baseline value, bronchial IgA/albumin ratio increased significantly (Day 3, +58%, p = 0.04); Day 14, +171%, p < 0.01), but serum IgA/albumin and serum and bronchial IgG/albumin ratios did not change significantly. In Group A, the increase in the IgA/albumin ratio was less than in Group B (Day 3, +15% versus +87%, p = 0.04; Day 14, +29% versus +210%, p < 0.01). No significant differences were observed between the two groups for bronchial and plasma albumin and IgG levels and for bronchial polymorphonuclear elastase levels. Bronchial IgA production was enhanced in ventilated patients. A reduction in this enhanced bronchial IgA production might account for the development of nosocomial pneumonia.

Adult↗
PubMed1994

Varicella-zoster virus infection of the central nervous system in the acquired immune deficiency syndrome.

Productive varicella-zoster virus (VZV) infection of the central nervous system (CNS) was demonstrated in 11 acquired immune deficiency syndrome (AIDS) patients using immunocytochemistry and in situ hybridization. A characteristic zoster skin eruption was seen in only four cases. From our own series and 11 other cases in the literature, we identified five clinico-pathological patterns of VZV infection of the CNS in AIDS patients which could occur simultaneously. (i) Multifocal encephalitis predominantly involving the white matter, likely to be due to haematogenous spread of the infection was found in four cases. (ii) Ventriculitis was found in three cases. In two cases there was complete acute or chronic necrosis of the ventricular wall with marked vasculitis; in the third, the ependymal lining appeared irregular with foci of VZV-infected ependymal cells, some of which protruded into the ventricular lumen. (iii) Acute haemorrhagic meningo-myeloradiculitis with necrotizing vasculitis was observed in two cases. In one, this was associated with ventriculitis and was possibly due to shedding of infected ependymal cells into the ventricular lumen and secondary seeding of the CSF. (iv) Focal necrotizing myelitis was seen in one case. It followed cutaneous herpes zoster and was considered to result from neural spread from the diseased dorsal root ganglion similar to cases previously described of encephalitis limited to the visual system following VZV ophthalmicus, or bulbar encephalitis following a trigeminal zoster. (v) Vasculopathy involving leptomeningeal arteries and causing cerebral infarcts was seen in four cases, it was associated with meningitis in most cases. These findings are in keeping with the observation in non-AIDS patients that VZV spread to the CNS may follow different routes. Our study tends to show that VZV infection of the CNS occurs more frequently in AIDS than previously suspected and suggests that it must be considered as a diagnosis in cases of encephalitis, ventriculitis, focal myelitis, acute myeloradiculitis and cerebral infarcts in these patients.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Zidovudine therapy and HIV encephalitis: a 10-year neuropathological survey.

OBJECTIVE: To assess the effect of zidovudine on productive HIV infection of the brain. DESIGN: To correlate the incidence of HIV-specific neuropathology with zidovudine therapy. PATIENTS: We examined 192 AIDS cases neuropathologically; 97 had never been treated with zidovudine, 72 had received zidovudine for over 3 months and until death, 23 had their treatment terminated more than 1 month before death. RESULTS: The incidence of HIV encephalitis/HIV leukoencephalopathy (HIVE/HIVL) and of multinucleated giant cells (MGC) was significantly lower in patients who had received zidovudine than in those who had never received zidovudine. The yearly incidence of HIVE/HIVL increased between 1982 and 1987 probably because of improved survival, and decreased between 1987 and 1990 although the percentage of patients treated with zidovudine increased. Since 1991 the incidence of HIVE/HIVL and of MGC increased slightly. The percentage of patients treated with zidovudine until death decreased and that of patients whose treatment was terminated increased concomitantly. In 1989 and 1990, most patients whose treatment was terminated had MGC and HIVE/HIVL. In 1991 and 1992 this incidence decreased markedly, coinciding with the introduction of dideoxyinosine therapy. CONCLUSION: Zidovudine treatment significantly reduces the occurrence of productive HIV infection of the brain in AIDS. Discontinuing zidovudine therapy may favour the occurrence of HIV encephalitis. Substitution therapy with dideoxyinosine also appears to protect against HIV-specific brain pathology.

AIDS Dementia Complex↗