Force recruitment during electrical nerve stimulation with multipolar intrafascicular electrodes

Experimentally, during electrical nerve stimulation, the influence is examined of two intrafascicular anodes on the force recruitment with one intrafascicular cathode. It is found that the anodes suppress recruitment and that this effect is more pronounced when the distance of the anodes to the cathode is decreased, or when the anodal currents are increased. The measured recruitment curve patterns can be qualitatively explained by a nerve stimulation model that calculates theoretical recruitment curves for intrafascicular multi-electrode configurations. Discrepancies between the experimental and the theoretical recruitment curves are seen, but these can be understood by taking into account a non-uniform fibre distribution.     

High survial rate of hamsters given intratracheal instillations of benzo[a]pyrene and ferric oxide and kept on a high {beta}-carotene diet

The study described in this paper was primarily conducted toidentify the cell types involved in the formation, progressionand regression of metaplastic changes in the respiratory tractepithelium of hamsters after intratracheal intubations withbenzo[a]pyrene Furthermore, the role of vitamin A and ß;-carotenein these processes was studied. In the course of the study aremarkable effect of dietary ß;-carotene on survivalof hamsters became a subject of investigation. Hamsters werefed diets with various levels of vitamin A or ß-caroteneand were treated intratracheally with a suspension of benzo[a]pyrenewith ferric oxide in saline. The tumour response of the respiratorytract was very low (2.8%) and hyper- and metaplasia of respiratoryepithelium were virtually absent. However, an interesting observationwas an exceptionally low mortality of only 2% after 69 weeksin the group of hamsters fed a high ß-carotene diet(1% w/w), whereas in the other groups mortality after 69 weeksamounted to 25%. Although the exact cause of death of most ofthe hamsters could not be established, a 40% reduction of lipidperoxidation in the livers was found in the high ß-carotenegroup. Moreover, In this group the degree and incidence of nephroslsand of focal mineralization of kidneys and heart were lowerthan in the other groups. These favourable effects of the highß-carotene diet may have contributed to the unusuallyhigh survival rate in hamsters fed this diet. Further studiesare planned to verify and study this observation.     

Use of commercially available cell culture inserts for primary culture and electrophysiologic studies of guinea pig gastric mucous epithelial cells

Summary The adherence, growth, and electrophysiologic properties of guinea pig gastric mucous epithelial cells were investigated using porous membrane filters. We also tested three commercially available Ussing-type chambers that were designed to be used with the various porous membrane supports. Overall, the 0.45-µm Falcon-Cyclopore porous membrane was found to be very favorable for the consistent attachment and growth of our cells. This same filter also gave good results in the detection of periodic acid Schiff-positive mucous glycoprotein and Nile red neutral lipid fluorescence in the gastric mucous cells. Our cells grew poorly on collagen-coated Costar-Snapwells and Millipore Millicell-CM porous filters. For measurement of transepithelial potential difference resistance, and short-circuit current, the Costar-Snapwell with the Costar-Snapwell Diffusion-chamber system was superior in design and operation when compared to the Costar Transwell-COL, Falcon-Cyclopore, or Anotec-Anocell porous inserts used with conventional Ussing-chambers. The gastric mucous cells grew best on ICN-Cellagen membranes, but these filters routinely detached from their plastic holder and therefore could not be used for Ussing-chamber studies. The large 24.5-mm, 0.40-µm pore size Costar-Transwell-COL and the 24.1-mm, 0.45-µm Falcon-Cyclopore membranes gave good results when used in a modified horizontal-chamber for microelectrode analysis of membrane potentials and resistances of the gastric mucous cell monolayers.     

Apert's syndrome with polymetatarsia]

Three cases of acrocephalosyndactyly with duplication of the first toe and presence of six well-individualized metatarsals are reported. This type of polysyndactyly should suggest the diagnosis of Carpenter syndrome, which is inherited on a recessive autosomal basis. However, in the three patients reported here, the facial dysmorphism was distinct from that seen in Carpenter syndrome and the syndactyly was more marked. The correct diagnosis therefore seems to be Apert acrocephalosyndactyly, a disease with dominant transmission. A mutation seems very likely and consequently the risk of recurrence in siblings is probably minimal.     

Effectiveness of gentamicin-impregnated cement in the prevention of deep wound infection after primary total knee arthroplasty.

Effectiveness of gentamicin-impregnated cement in preventing deep wound infection after total knee arthroplasty (TKA) was estimated using data from prospective surveillance. In multivariate analysis, the protective effect of gentamicin-impregnated cement on the development of infection was close to the limit of significance. Gentamicin-impregnated cement may prevent TKA infections.     

Progressive myelopathy due to meningeal thickening in shunted patients: description of a novel entity and the role of surgery

INTRODUCTION: Spinal cord compression due to meningeal thickening is a rare occurrence in shunted patients. Because of the long delay to clinical onset, this complication has not been identified as yet. AIMS: We report on nine cases of shunt-related progressive myelopathy due to meningeal thickening (SPMMT). MATERIALS AND METHODS: We reviewed our database of shunted children, for cases having developed progressive tetraparesis due to cervical meningeal thickening. RESULTS: We identified nine observations of SPMMT, eight of these with hydrocephalus due to neonatal meningitis; the last case had Dandy-Walker malformation shunted at birth and suffered postoperative meningitis. The age of clinical onset of myelopathy was between 6 and 20 years (median 12.8). All patients presented with slowly progressive walking difficulties with falls and no spinal pain. Magnetic resonance imaging (MRI) showed typically a thickened dura mater with collapse of the arachnoid space, compensatory expansion of the epidural fat, and T2 hyperintensity in the spinal cord. We operated on seven patients for surgical decompression and arachnoidolysis: One died postoperatively because of shunt malfunction, and two others died later of complications of tetraplegia. Three patients were aggravated after surgery, three experienced partial improvement, but one of these subsequently deteriorated again. CONCLUSION: SPMMT appears to be a novel and well-defined clinical and pathological entity; its pathological and radiological features are stereotyped; however, the diagnosis is delayed because of the slow pace of the disease. Although surgical decompression may be the only option, its results were poor in our experience; earlier surgery might improve this grim prognosis.     

Quantification of HIV-1 p24 by a highly improved ELISA: an alternative to HIV-1 RNA based treatment monitoring in patients from Abidjan, C?te d'Ivoire.

BACKGROUND: Quantification of HIV-1 RNA remains difficult to implement in Africa. Simple and inexpensive tests for antiretroviral treatment (ART) monitoring are needed. OBJECTIVE: To evaluate an HIV-1 p24 ELISA, which combines efficient virus disruption, heat-denaturation and signal amplification, in a West African setting. STUDY DESIGN: Eighty-six HIV-1 infected patients from Abidjan, C?te d'Ivoire, were tested for p24, HIV-1 RNA, and CD4+ count at baseline, and twice within 8 months after ART initiation. RESULTS: All patients responded to ART with a minimal HIV-1 RNA drop of 0.5 log(10) at first follow-up. Forty-one (47.7%) then rebounded >0.5 log(10) or persisted above 1000 copies/mL by week 24. The predicted baseline concentration of p24 corresponding to 100,000 copies/mL of HIV-1 RNA, above which ART is recommended, was 4546 fg/mL (95% confidence interval 3148-6566). A prediction model of virologic failure, occurring after an initial response to ART, correctly classified 84% of patients using baseline p24, p24 change on therapy, and achievement of undetectable p24 as explanatory variables. The model and further bootstrap evaluation suggested a good ability to discriminate between sustained or failing virologic response to ART. CONCLUSION: HIV-1 p24 and RNA based-ART monitoring in a low-resource country dominated by HIV-1 CRF02 AG appeared comparable.     

Long-term adhesion and survival of dissociated cortical neurons on miniaturised chemical patterns

The influence of neuron-adhesive pattern geometry on long-term adhesion, survival and pattern compliance of cortical neuronal tissue was studied over a period of 15 days. The results are relevant for a successful, long-term integration of neuronal cells with electrodes from micro-electronic devices. Microwells (depth 0.5μm), with diameters of 25, 50, 100 and 150 μm and spacing distances of 15, 30, 60 and 90 μm, were etched in a neuron-repellent fluorocarbon (FC) layer and coated with neuron-adhesive polyethylenimine (PEI). Results showed that adhesion, survival and compliance to the underlying patterns were geometry-and time-dependent. After 1 day, adhesion was inversely proportional to the diameter of the microwells, thus favouring the 25 μm microwells. However, adhesion was best on 50 μm microwells after 15 days. Survival of neurons was limited on 25 μm microwells (viability function V(D, T) was 0.08), as opposed to the better survival on 150 μm microwells (V(D, T) was 0.25) after 15 days. In summary, the study shows that the chemical patterns with microwells of 150 μm diameter (90 μm spacing gap) are most suitable for application on neuro-electronic devices owing to the better long-term survival and high pattern compliance of the neuronal cells.     

In vivo autofluorescence imaging of early cancers in the human tracheobronchial tree with a spectrally optimized system

The changes in the autofluorescence characteristics of the bronchial tissue is of crucial interest as a cancer diagnostic tool. Evidence exists that this native fluorescence or autofluorescence of bronchial tissues changes when they turn dysplastic and to carcinoma in situ. There is good agreement that the lesions display a decrease of autofluorescence in the green region of the spectrum under illumination with violet-light, and a relative increase in the red region of the spectrum is often reported. Imaging devices rely on this principle to detect early cancerous lesions in the bronchi. Based on a spectroscopic study, an industrial imaging prototype is developed to detect early cancerous lesions in collaboration with the firm Richard Wolf Endoskope GmbH, Germany. A preliminary clinical trial involving 20 patients with this spectrally optimized system shows that the autofluorescence can help to detect most lesions that would otherwise have remained invisible to an experienced endoscopist under white light illumination. A systematic off line analysis of the autofluorescence images pointed out that real-time decisional functions can be defined to reduce the number of false positive results. Using this method, a positive predictive value (PPV) of 75% is reached using autofluorescence only. Moreover, a PPV of 100% is obtained, when combining the white light (WL) mode and the autofluorescence (AF) mode, at the applied conditions. Furthermore, the sensitivity is estimated to be twice higher in the AF mode than in WL mode.