An Air-Gap Enzyme Electrode: Development and Applications

A novel air-gap enzyme electrode was developed by amalgamating the principles controlling ion-selective electrodes, enzyme kinetics, and diffusion of molecules across membranes. Commercially available ammonia and carbon dioxide gas-sensing electrodes were modified to measure the respective gases over a head-space. A plexiglass cell was designed and fabricated to house the modified electrodes. The air-gap electrodes exhibited superior sensitivity and response characteristics compared to the original membrane electrodes. The plexiglass cell was divided into two compartments by virtue of a selectively permeable membrane. Enzymatic reactions were conducted in the cell to determine quantitatively the concentration of the substrate. L-Phenylalanine ammonia lyase was used to determine L-phenylalanine with the ammonia electrode and L-glutamate decarboxylase was utilized for the determination of L-glutamic acid by the carbon dioxide electrode. Near-Nernstian slopes were obtained for the response of the enzyme electrodes. In addition to the good reproducibility, the method provided unique ability to reuse the same enzyme solution for several determinations of various concentrations of the analyte. The performance of the two compartment cell and air-gap enzyme electrode was found to be superior in comparison to conventional enzyme electrodes.     

Epilepsy Surgery in Infants

Purpose: We report 12 infants who had frontal (n = 3), temporal (n = 2), or temporoparieto-occipital (n = 2) resection or functional hemispherectomies (n = 5) at age 2.5–29 (mean 15.3) months for catastrophic epilepsy due to focal cortical dysplasia (n = 5), Sturge-Weber syndrome (n = 3), ganglioglioma (n = 3), or hemimegalencephaly (n = 1). Seizures began at 1 day to 14 months (mean, 4.0 months) after birth, occurred frequently (often many times per day, and were refractory to antiepileptic drugs. Patients were evaluated for surgery at 2.5–24 (mean 12.4) months of age. Seven patients had hemiparesis and eight had slowed cognitive development. Seizures were characterized by arrest or marked reduction of behavioral motor activity with unclear level of consciousness (n = 4, with temporal or temporoparietal EEG seizures), focal clonic activity (n = 3, with perirolandic EEG seizures), generalized tonic stiffening (n = 3, with temporoparieto-occipital, parietal, or frontal EEG seizures), or infantile spasms and hypsarrhythmia (n = 2, with a frontal tumor or temporoparieto-occipital cortical dysplasia). Methods: Magnetic resonance imaging (MRI) revealed the epileptogenic lesion in all but two patients, both with cortical dysplasia localized by interictal positron-emission tomography (PET) and other clinical or EEG features and confirmed on histopathologic examination of resected tissue. Results: At follow-up 4-86 (mean 32) months after surgery, six patients were seizure free (Engel outcome class I), three had rare seizures with none in at least the previous 6 months (Engel class II), and two had worthwhile improvement (Engel class III). Except for the severely developmentally delayed infant with hemimegalencephaly, several patients had marked “catch-up” developmental progress after class I, 11, or III outcome. Postoperative complications included subdural hematoma over the contralateral hemisphere (one patient) and entrapment and enlargement of the ipsilateral temporal horn (one patient) after hemispherectomy, both corrected uneventfully with a second surgical procedure. One patient died of unexplained causes several hours after frontal lobectomy. No patients had new neurologic deficits after surgery, and one patient had resolution of progressive fluctuating hemiparesis after resection of temporoparieto-occipital cortical dysplasia. Conclusions: Our results agree with previous reports that epilepsy surgery can provide relief from catastrophic epilepsy in carefully selected infants.     

Quality systems in automated plateletpheresis in hospital-based blood transfusion service in north India

The issues of providing quality blood products and maintaining donor safety are primary aims of blood transfusion services. A comprehensive quality system should be in place to fulfill these aims, which can be attained through strict adherence to the established standard operating procedures (SOPs). The Drugs and Cosmetics Act of India, which controls the licensing of blood transfusion services, does not provide clear guidelines regarding plateletpheresis procedure. We, therefore, established our own SOP and operational flow chart for plateletpheresis that can be easily followed by other centers in India. A total of 100 plateletpheresis procedures performed using two cell separators (CS3000 Baxter Healthcare, Round Lake, IL; MCS3p, Haemonetics Corporation, Braintree, MA) were evaluated following our established SOP. The mean platelet yield in CS3000 was 2.9 +/- 0.84 x 10(11) and in MCS3p it was 2.88 +/- 0.75 x 10(11)per unit. However, only 4-7% of SDPs showed WBC levels <5 x 10(6) due to lack of appropriate methods to quantitate residual WBC counts. Six of 100 donors complained of hypocalcemic symptoms. The operational flow chart designed in this study was found to be simple and easy to adapt by blood transfusion services in this country.     

Giant intradiploic pseudomeningocele of occipital bone

The management of intradiploic CSF collection is controversial. Although it is a benign lesion, even then delay in diagnosis and treatment may lead to significant morbidity. The authors report a very rare case of giant posttraumatic intradiploic pseudomeningocele involving the occipital bone, occipital condyles, and clivus. The pathogenesis and management of intradiploic CSF collection are discussed. This 16-year-old boy presented with a history of enlarging swelling in the suboccipital region associated with headache, lower cranial nerve palsy, and features of high cervical compressive myelopathy. Investigations revealed a giant intradiploic lesion involving the occipital bone, condyles, and clivus associated with secondary basilar invagination, hydrocephalus, and syringomyelia. Intrathecal contrast administration did not reveal communication of intradiploic space with the subarachnoid space. A large occipital craniotomy was performed. A linear fracture and dural defect in the midline was identified, which was closed with fascial graft after removing the inner table of the skull. Cranioplasty was performed using the expanded calvarial bone. Ventriculoperitoneal shunt insertion was performed for hydrocephalus, and the patient improved remarkably. Posttraumatic intradiploic CSF collection, although a benign condition, may present with severe complications if treatment is delayed. Early diagnosis and treatment is essential. The authors suggest that this condition should be treated early, as for growing skull fractures.     

Spinal nerve lesion alters blood-spinal cord barrier function and activates astrocytes in the rat

Alterations in the spinal cord microenvironment in a neuropathic pain model in rats comprising right L-4 spinal nerve lesion were examined following 1, 2, 4 and 10 weeks using albumin and glial fibrillary acidic protein (GFAP) immunoreactivity. Rats subjected to nerve lesion showed pronounced activation of GFAP indicating astrocyte activation, and exhibited marked leakage of albumin, suggesting defects of the blood-spinal cord barrier (BSCB) function in the corresponding spinal cord segment. The intensities of these changes were most prominent in the gray matter of the lesioned side compared to the contralateral cord in both the dorsal and ventral horns. The most marked changes in albumin and GFAP immunoreaction were seen after 2 weeks and persisted with mild intensities even after 10 weeks. Distortion of nerve cells, loss of neurons and general sponginess were evident in the gray matter of the spinal cord corresponding to the lesion side. These nerve cell and glial cell changes was mainly evident in the areas showing leakage of endogenous albumin in the spinal cord. These novel observations indicate that chronic nerve lesion has the capacity to induce a selective increase in local BSCB permeability that could be instrumental in nerve cell and glial cell activation. These findings may be relevant to our current understanding on the pathophysiology of neuropathic pain.     

Selective serotonin depletion does not regulate hippocampal neurogenesis in the adult rat brain: differential effects of p-chlorophenylalanine and 5,7-dihydroxytryptamine

Serotonin is suggested to regulate adult hippocampal neurogenesis, and previous studies with serotonin depletion reported either a decrease or no change in adult hippocampal progenitor proliferation. We have addressed the effects of serotonin depletion on distinct aspects of adult hippocampal neurogenesis, namely the proliferation, survival and terminal differentiation of hippocampal progenitors. We used the serotonin synthesis inhibitor p-chlorophenylalanine (PCPA) or the serotonergic neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) to deplete serotonin levels. 5,7-DHT selectively decreased hippocampal serotonin levels, while PCPA resulted in a significant decline in both serotonin and norepinephrine levels. We observed a robust decline in the proliferation and survival of adult hippocampal progenitors following PCPA treatment. This was supported by a decrease in the number of doublecortin-positive cells in the neurogenic niche in the hippocampus. In striking contrast, 5,7-DHT did not alter the proliferation or survival of adult hippocampal progenitors and did not alter the number of doublecortin-positive cells. The terminal differentiation of adult hippocampal progenitors was not altered by either PCPA or 5,7-DHT treatment. An acute increase in serotonin levels also did not influence adult hippocampal progenitor proliferation. These results suggest that selective serotonin depletion or an acute induction in serotonin levels does not regulate adult hippocampal neurogenesis, whereas treatment with PCPA that induces a decline in both serotonin and norepinephrine levels results in a significant decrease in adult hippocampal neurogenesis. Our results highlight the need for future studies to examine the role of other monoamines in both the effects of stress and antidepressants on adult hippocampal neurogenesis.     

A Soft,Flexible Stent/Bung for Marsupialisation

A soft flexible stent or bung for marsupialisation using putty elastomeric impression material rather than an acrylic bung.     

Lower material stiffness in rupture-repaired Achilles tendon during walking: transmission-mode ultrasound for post-surgical tendon evaluation

Purpose

This cross-sectional study used transmission-mode ultrasound to evaluate dynamic tendon properties during walking in surgically repaired and contralateral Achilles tendon (AT), with a median (range) post-operative period of 22 (4–58) months. It was hypothesised that the axial transmission speed of ultrasound (TSOU) during walking would be slower, indicating lower material stiffness in repaired compared with contralateral AT.

Methods

Ten patients [median (range) age 47 (37–69) years; height 180 (170–189) cm; weight 93 (62–119) kg], who had undergone open surgical repair of the AT and were clinically recovered according to their treating clinicians, walked barefoot on a treadmill at self-selected speed (1.0 ± 0.2 m/s). Synchronous measures of TSOU, sagittal ankle motion, vertical ground reaction force (GRF), and spatiotemporal gait parameters were recorded during 20 s of steady-state walking. Paired t tests were used to evaluate potential between-limb differences in TSOU, GRF, ankle motion, and spatiotemporal gait parameters.

Results

TSOU was significantly lower (≈175 m/s) in the repaired than in the contralateral AT over the entire gait cycle (P < 0.05). Sagittal ankle motion was significantly greater (≈3°) in the repaired than in the contralateral limb (P = 0.036). There were no significant differences in GRF or spatiotemporal parameters between limbs.

Conclusions

Repaired AT was characterised by a lower TSOU, reflecting a lower material stiffness in the repaired tendon than in the contralateral tendon. A lower material stiffness may underpin greater ankle joint motion of the repaired limb during walking and long-term deficits in the muscle-tendon unit reported with AT repair. Treatment and rehabilitation approaches that focus on increasing the material stiffness of the repaired AT may be clinically beneficial. Transmission-mode ultrasound would seem useful for quantifying tendon properties post AT rupture repair and may have the potential to individually guide rehabilitation programmes, thereby aiding safer return to physical activity.

Level of evidence

II.

     

Immunomodulatory basis of antioxidant therapy and its future prospects: an appraisal

Antioxidants are agents which can modulate oxidant–antioxidant profile of body system by neutralizing pro-oxidant molecules. The current scientific knowledge on mechanisms of antioxidant activity of biomolecules was critically reviewed with a special emphasis on immunomodulation. The immuno-oxidative wreckage of animals in various disease conditions and the role of biomodulators in curbing the oxidative stress through immune pathways were analyzed. The critical role of immunomodulatory mechanisms in controlling oxidative damage was identified. Selection of antioxidant therapy considering the immunopharmacology of the drug as well as immunological basis of disease may reduce treatment failure and adverse health effects. Hence, it is suggested that future studies on antioxidants may focus on the immuno-oxidative pathobiology to better understand its clinical effects and effective disease management.