Post-acute stroke patients use brain-computer interface to activate electrical stimulation.

Through certain mental actions, our electroencephalogram (EEG) can be regulated to operate a brain-computer interface (BCI), which translates the EEG patterns into commands that can be used to operate devices such as prostheses. This allows paralyzed persons to gain direct brain control of the paretic limb, which could open up many possibilities for rehabilitative and assistive applications. When using a BCI neuroprosthesis in stroke, one question that has surfaced is whether stroke patients are able to produce a sufficient change in EEG that can be used as a control signal to operate a prosthesis.

Evaluation of robotic-assisted locomotor training outcomes at a rehabilitation centre in Singapore.

INTRODUCTION: The aim of this study was to determine whether robotic-assisted locomotor training, a new clinical service introduced at the Tan Tock Seng Hospital (TTSH) Rehabilitation Centre, Singapore is effective at improving the ability to transfer and the ambulatory status of patients with an acquired brain injury. METHODS: This was a retrospective review of data collected from patients with an acquired brain injury, before and after robotic-assisted locomotor training from September 2008 to May 2009. The primary outcome measures used were the functional independence measure (FIM) for transfer and ambulation, and the Rivermead Motor Assessment (RMA) gross function subscale. The secondary outcome measures used were the Motricity Index (MI) and Modified Ashworth Scale of the lower limb. Statistical analysis was performed on this data to evaluate whether robotic-assisted locomotor training was effective at improving the functional mobility of these patients. RESULTS: Significant improvement was observed in the scores of FIM transfer (p is less than 0.05), FIM ambulation (p is less than 0.05) and RMA (p is less than 0.05) after robotic-assisted locomotor training. Significant improvements in the MI of hip flexion (p is less than 0.05), knee extension (p is less than 0.05) and ankle dorsiflexion (p is less than 0.05) post training have also been noted. CONCLUSION: Robotic-assisted locomotor training was found to be effective at improving the transfer, ambulation and functional mobility of patients with an acquired brain injury.

Mapping the high-affinity binding domain of 5-substituted benzimidazoles to the proximal N-terminus of the GluN2B subunit of the NMDA receptor.

BACKGROUND AND PURPOSE: N-methyl-D-aspartate (NMDA) receptors represent an attractive drug target for the treatment of neurological and neurodegenerative disorders associated with glutamate-induced excitotoxicity. The aim of this study was to map the binding domain of high affinity 5-substituted benzimidazole derivatives [N-{2-[(4-benzylpiperidin-1-yl)methyl]benzimidazol-5-yl}methanesulphonamide (XK1) and N-[2-(4-phenoxybenzyl)benzimidazol-5-yl]methanesulphonamide (XK2)] on the GluN2B subunit of the NMDA receptor. EXPERIMENTAL APPROACH: The pharmacological antagonistic profiles of XK1 and XK2 were assessed using in vitro rat primary cerebrocortical neurones and two-electrode voltage clamp on Xenopus oocytes expressing heterologous GluN1/GluN2B receptors. Direct ligand binding was determined using the recombinant amino-terminal domain (ATD) of GluN2B. KEY RESULTS: XK1 and XK2 effectively protected against NMDA-induced excitotoxicity in rat primary cortical neurones. Low concentrations of XK1 (10 nM) and XK2 (1 nM) significantly reversed neuronal death. Both compounds failed to inhibit currents measured from oocytes heterologously expressing GluN1-1a subunit co-assembled with the ATD-deleted GluN2B subunit. XK1 and XK2 showed specific binding to recombinant protein of GluN2B ATD with low nanomolar affinities. Several residues in the recombinant ATD of GluN2B were identified to be critical for conferring XK1 and XK2 sensitivity. The inhibitory effects of XK1 and XK2 were pH-sensitive, being increased at acidic pH. CONCLUSIONS AND IMPLICATIONS: These results demonstrate that XK1 and XK2 are effective neuroprotective agents in vitro and indicate that 5-substituted benzimidazole derivatives inhibit GluN1/GluN2B receptors via direct binding to the ATD of the GluN2B subunit. These compounds represent valuable alternatives to the classical antagonist ifenprodil as pharmacological tools for studying GluN2B-containing NMDA receptors.

Deep vein thrombosis based on D-dimer screening in ischaemic stroke patients undergoing rehabilitation.

INTRODUCTION: Although lower extremity deep vein thrombosis (DVT) is a common complication after an acute stroke, there is little local data documenting this condition in stroke patients undergoing rehabilitation. The purpose of this study was to determine the frequency and risk factors of DVT in ischaemic stroke patients admitted to a rehabilitation unit. METHODS: This was a prospective observational single-centre study of ischaemic stroke patients with lower limb paresis admitted to a rehabilitation centre. The screening protocol consisted of quantitative D-dimer assay (DDA) within 24-48 hours of rehabilitation admission followed by duplex Doppler ultrasonography (DUS) of the paretic lower extremity if the DDA level was elevated (equal or greater than 0.34 micro/ml). RESULTS: 212 patients (167 Chinese, 27 Malays, 17 Indians and one Eurasian) were screened at a mean of 23.2 days post-stroke. 121 (57.1 percent) patients had an elevated DDA, and all underwent ultrasonography. The incidence of lower limb DVT was 5.2 percent (11), consisting of four proximal and seven distal. DVT was significantly related to total anterior circulation infarct (odds ratio 3.69, 95 percent confidence interval 1.04-3.05, p-value is 0.043), but not to age, gender, race, severity of lower limb weakness, and ambulatory and functional status. No patients had clinical pulmonary embolism during rehabilitation. CONCLUSION: Locally, asymptomatic lower limb DVT based on a screening protocol of DDA and selective DUS, is uncommon in ischaemic stroke patients admitted to rehabilitation. Future research efforts could include a detailed evaluation of DDA's role as a screening tool for DVT in the stroke population, by comparing it to an established gold standard like venography.

Deep vein thrombosis in stroke patients admitted to a rehabilitation unit in Singapore.

BACKGROUND: Studies have shown that deep vein thrombosis (DVT) is common after an acute stroke. Less common are studies documenting DVT in stroke patients admitted to rehabilitation. The purpose of this study was to determine the frequency and risk factors of DVT in stroke patients admitted to a rehabilitation unit in Singapore. METHODS: A prospective observational single-center study of patients with ischemic and hemorrhagic stroke with lower limb paresis admitted to a rehabilitation center in Singapore. The screening protocol consisted of quantitative D-dimer assay (DDA) within 24-48 h of rehabilitation admission followed by duplex ultrasound scan of the paretic lower extremity if DDA level was elevated (equal or greater than 0.34 microg/ml). RESULTS: Altogether, 341 patients were screened at a mean of 23 days poststroke. One hundred and ninety-eight (58.1%) patients had an elevated DDA and all underwent ultrasound scans. The frequency of lower limb DVT was 9% (18) - seven proximal and 11 distal. DVT was significantly related to higher D-dimer levels (P=0.029) and cortical strokes (P=0.004), but not to age, gender, race, nature of stroke, atrial fibrillation, severity of lower limb weakness, and ambulatory and functional status. No patients had clinical pulmonary embolism during rehabilitation. CONCLUSIONS: Lower limb DVT is uncommon in stroke patients admitted to rehabilitation in Singapore. Future research should include evaluation of the cost-effectiveness of such a screening protocol.

Akinetic mutism after right internal watershed infarction.

We describe a 72-year-old man who developed akinetic mutism following a cerebrovascular accident involving his right internal watershed area and responded well to dopaminergic agonists. We discuss this rare condition and the unusual unilateral location of the lesion.

Complete semimembranosus rupture following therapeutic stretching after a traumatic brain injury.

Acute hamstring rupture is an uncommon event often occurring during high impact sports. Such events have not been previously reported during neurological rehabilitation. This case report describes a 30 year-old Chinese male presenting in a minimally responsive state 5 years after a severe traumatic brain injury. He was tetraplegic and bed-bound with spasticity involving all four limbs and flexion contracture of the right knee. During an episode of inpatient rehabilitation, he developed acute swelling and bruising of the posterior proximal thigh region associated with fever, tachycardia and diaphoresis. MRI showed a large soft tissue rim-enhancing mass in the right proximal hamstring muscle. During surgical exploration, complete rupture of the right semi-membranosus muscle was found without evidence of pus. The possible causative factors of hamstring rupture in this subject and a brief literature review are discussed. To the authors' knowledge, this is the first such reported case.

Health-related quality of life among chronic stroke survivors attending a rehabilitation clinic.

INTRODUCTION: To assess health-related quality of life (HRQOL) among chronic stroke survivors and factors associated with it. METHODS: Cross-sectional survey study of patients who had survived one year or more after a stroke. Subjects consisted of stroke patients attending the outpatient clinic of a rehabilitation centre. HRQOL was assessed using the Medical Outcomes 36-Item Short-Form Health Survey (SF-36), functional status using the Modified Barthel Index (MBI), and mood using the Beck's Depression Inventory (BDI). RESULTS: A total of 100 patients (63 men and 37 women, mean age 60.7 +/-10.8 years) were interviewed at an average of 22.2 +/-14.5 months post-stroke. The mean MBI was 88.9 +/-17.9, and the prevalence of depression 24%. 50 percent of patients needed varying degrees of care for their activities of daily living. The SF-36 scores of the patients were comparable to that of the general population except for the domain of physical function, which was much lower (23.9 versus 83.4). Age, sex, post-stroke duration, MBI score and side of hemiplegia were not associated with HRQOL. Depressed patients however had significantly lower SF-36 scores across all domains except for that of physical function and bodily pain (p-value is less than 0.001). CONCLUSION: A significant proportion of chronic stroke survivors attending the rehabilitation clinic continue to face limitations in their physical activities. In addition, almost 30 percent of these survivors have depression that affects their HRQOL adversely.

An unusual case of Dantrolene sodium-induced urinary retention in post-traumatic minimally responsive state.

INTRODUCTION: An unusual case of urinary retention is reported occurring during the inpatient rehabilitation of minimally responsive state (MRS) following severe traumatic brain injury (TBI). CLINICAL PICTURE: Urodynamic evaluation showed detrusor acontractility and subsequent management involved intermittent bladder catheterization and treatment of a single urinary tract infection. TREATMENT: Factors contributing to her bladder paralysis included severe immobility, tetraplegia and treatment of diffuse spasticity with oral Dantrolene sodium 250 mg per day. Constipation, diabetes and spinal cord injury were absent. In addition, she received unilateral partial sciatic neurolysis with 50% alcohol for severe knee flexor spasticity and intra-muscular Botulinum toxin A to both spastic upper limbs. OUTCOME: Bladder acontractility resolved completely when Dantrolene was reduced with subsequent achievement of a catheter-free status and small post-void residual volumes. Repeat urodynamics showed spontaneous detrusor contractions. CONCLUSION: A discussion of possible aetiologic factors for detrusor acontracility following TBI is presented including a brief review of the literature.

Pain during in-patient rehabilitation after traumatic spinal cord injury.

In this prospective study, we surveyed the pain experience of 40 participants during the in-patient rehabilitation period following traumatic spinal cord injury (SCI). Twenty-eight patients (70% of the study population) had musculoskeletal (MS) pain or neuropathic (NP) pain. Pain responded positively to physical therapy and analgesics. A numerical pain scale decreased from a mean of 6.36+/-1.7 on admission to 3.2+/-1.94 on discharge (P<0.001). Paraplegic patients were more likely to have MS pain (P=0.001) and NP pain (P=0.046). There was no relationship between completeness of injury, or spinal surgery, and type of pain encountered. There was also no significant difference in the modified Barthel index between patients with and without pain on admission and discharge. We conclude that pain is a common experience in SCI patients and that it can be reduced significantly by the end of in-patient rehabilitation.

Urinary incontinence after traumatic brain injury: incidence, outcomes and correlates.

OBJECTIVES: To document the incidence and outcome of urinary incontinence (UI) and urinary retention (UR) during acute traumatic brain injury (TBI) rehabilitation and determine associated clinical variables. METHODS: Retrospective case series. RESULTS: Eighty-four patients (mean age 44.7 +/- 17.9 years; 66 males, 18 females) with first-ever TBI within 6 weeks of injury. On admission, UI was present in 52 (62%). UR defined as post-void residual urine volumes of > 100 mls was present in eight (9.5%). Forty-six (54.8%) needed external collecting devices and six (7.1%) used indwelling catheters. Bilateral lesions, diabetes mellitus and faecal impaction were present in 70.2, 10.7 and 6.0%, respectively. UI was associated with poorer functional status (measured by the modified Barthel index) and presence of bilateral lesions (p < 0.01). UR was associated with diabetes mellitus and faecal impaction (p < 0.01). On discharge, 31 (36.9%) remained incontinent. CONCLUSION: UI is common after acute TBI and is associated with poorer functional outcome.

Acquired heterotopic ossification in the settings of cerebral anoxia and alternative therapy: two cases.

Acquired Heterotopic Ossification (HO) has been well described in the literature as a recognized complication following spinal cord injury, traumatic brain injury and joint arthroplasty. Commonly, large proximal limb joints are affected. The underlying mechanisms for ectopic bone formation remain poorly elucidated. Post-stroke hemiplegia as a cause of neurogenic HO is rare, and no published reports of HO occurring after anoxic brain injury in adults have been documented. This study reports two unusual cases of acquired HO: (1) Polyarticular HO involving the ankle joint in a 24-year-old Chinese female who suffered severe anoxic encephalopathy following near drowning which resulted in persistent vegetative state; and (2) Elbow HO in chronic post-stroke hemiplegia occurring as a complication of alternative therapy following repeated forceful manipulation by a traditional practitioner in a 46 year-old male.

Intramuscular neurolysis with alcohol to treat post-stroke finger flexor spasticity.

OBJECTIVE: To evaluate the effectiveness of intramuscular neurolysis with alcohol for the treatment of finger flexor spasticity in individuals with stroke. DESIGN: Case series. SETTING: Outpatient clinic of a tertiary rehabilitation facility. SUBJECTS: Thirty patients with a mean age of 60.2 years and post-stroke duration of 8.3 months with finger flexor spasticity. INTERVENTIONS: Intramuscular neurolysis or motor point blocks of the finger flexors of the hemiplegic upper extremity with 50% ethyl alcohol. MAIN OUTCOME MEASURES: The severity of spasticity as measured by the Modified Ashworth Scale (MAS) and the passive range of motion of the proximal interphalangeal joints of the second to fifth digits. RESULTS: The mean baseline MAS score was 4.0 +/- 0.5 and this improved to 2.0 +/- 0.6, 2.2 +/- 0.6 and 2.6 +/- 0.6 at four weeks, three months and six months post neurolysis respectively. The gains in range of motion were 18.5 +/- 6.7, 17.5 +/- 6.4 and 14.9 +/- 4.8 degrees at four weeks, three months and six months post neurolysis respectively. These improvements were statistically significant (p < 0.05). Two subjects developed temporary dysesthetic pain of the forearm and palm. CONCLUSION: Intramuscular neurolysis with alcohol provides good relief of finger flexor spasticity in hemiplegic individuals.

The prevalence and descriptive epidemiology of atopic dermatitis in Singapore school children.

BACKGROUND: Atopic dermatitis is a common disease that appears to be increasing in frequency during recent decades. Most of the studies are based on the Western population, and there are few data in the Asian population. OBJECTIVES: To determine the prevalence and descriptive epidemiology of atopic dermatitis among school children in the general community in Singapore. METHODS: This is a questionnaire study of 12 323 students done over a 1-year period, comprising 7 year olds (4605), 12 year olds (3940) and 16 year olds (3778) from 19 primary and 17 secondary schools randomly selected in Singapore. All children had a complete cutaneous examination. The diagnosis of atopic dermatitis was based on the U.K. Working Party diagnostic criteria. The questionnaire was translated into Chinese and both the English and Chinese versions were issued simultaneously to the students. RESULTS: The 1-year period prevalence of atopic dermatitis was 20.8%. Atopic dermatitis was present in 22.7% of 7 year olds, 17.9% of 12 year olds and 21.5% of 16 year olds. The overall sex ratio was equal. There were slightly more boys with atopic dermatitis among the younger children (6 and 12 year olds, 1.18 : 1 and 1.19 : 1, respectively) but more girls were affected (1.57 : 1) among the 16 year olds. Atopic dermatitis was more common among the Chinese (21.6%) and Malays (19.8%) compared with the Indians (16%) and other races (14%). The onset of the disease occurred before the age of 10 years in 49.5% of the 16 year olds. "Pure" atopic dermatitis without concomitant respiratory allergies was noted in 788 respondents (30.7%); 1775 (69.3%) suffered from a "mixed" type, with 34.3% having allergic rhinitis, 9.5% having asthma and 25.5% having both asthma and allergic rhinitis. More boys had atopic dermatitis and concomitant respiratory allergies whereas more girls were affected with "pure" atopic dermatitis alone (1.4 : 1). At least one first-degree family member with atopy was noted in 1435 children (56%): atopic dermatitis (70%), asthma (62%) and allergic rhinitis (68%). Among siblings with one parent with atopic dermatitis, 37% had either a father or a mother with atopic dermatitis. Common aggravating factors reported included exercise, heat and sweating, grass intolerance, thick clothing and stress. Pityriasis alba was noted in 25% of the study population, keratosis pilaris in 13% and ichthyosis vulgaris in 8%. Most respondents had mild to moderate atopic dermatitis that could be controlled with a fairly simple regimen of moisturizers, topical steroids, antihistamines and antibiotics. CONCLUSIONS: The high prevalence of atopic dermatitis in Singapore is similar to that observed in developed countries, suggesting that environmental factors may be important in determining the expression of the disease.

Clinical and functional outcome after alcohol neurolysis of the tibial nerve for ankle-foot spasticity.

PURPOSE: To report one's experience of using 50-100% alcohol for neurolysis of the tibial nerve in chronic ankle-foot spasticity. METHODS: The records of patients who received alcohol neurolysis of the tibial nerve were retrospectively reviewed. Repetitive monopolar nerve stimulation was used to localize the tibial nerve. Outcome measures included muscle tone as measured by the Modified Ashworth Score (MAS), passive ankle range of motion (PROM), effect on clonus, plantar flexor motor strength, visual gait analysis and use of orthoses. RESULTS: A total of 21 tibial nerves were neurolysed in 18 patients (mean age 38.9 +/- 15.8 years, 12 males, six females). Mean duration post-event was 14.8 +/- 3.9 months. The mean pre-neurolysis MAS was 2.50 +/- 0.77 and this improved to 0.97 +/- 0.88 (p < 0.001) and 0.93 +/- 0.85 (p < 0.001) at 1 and 6 months post-procedure, respectively. Average duration of effect was 10.5 +/- 8.9 months. Eleven out of 12 patients (91.7%) with sustained ankle clonus had complete abolishment lasting 6 months. Mean gain in PROM was 24.6 +/- 16.1 degrees and 32.6 +/- 19.0 degrees at 1 and 3 months post-neurolysis, respectively (p < 0.001, < 0.02). No decrease in motor strength was seen post-neurolysis. All 13 ambulant patients had visible improvements in gait. Complications were transient and included dysesthetic pain (4), sensory loss (1) and distal limb oedema (1). CONCLUSION: Alcohol neurolysis (50-100%) of the tibial nerves is an effective and safe method of managing ankle-foot spasticity.

Incidence and outcome of poststroke urinary retention: a prospective study.

OBJECTIVE: To document the incidence and outcome of poststroke urinary retention, and to determine clinical variables associated with it. DESIGN: Cohort of 80 consecutive patients. SETTING: Inpatient setting of a tertiary rehabilitation center. PARTICIPANTS: Eighty patients (48 men, 32 women; mean age, 65.4 yr) with a first ischemic stroke, admitted for rehabilitation within 4 weeks of the stroke. MAIN OUTCOME MEASURES: Patients had their postvoid residuals (PVR) assessed via a bladder scanner within 72 hours of admission. Urinary retention was defined by a PVR of more than 100mL on 2 consecutive occasions. RESULTS: Urinary retention was present in 23 (29%) patients. Cognitive impairment, aphasia, diabetes mellitus, and cortical stroke were present in 30%, 29%, 31%, and 41% of patients, respectively. Fifteen (19%) patients developed urinary tract infection during rehabilitation. Urinary retention was significantly associated (p < .05) with cognitive impairment, diabetes mellitus, aphasia, a lower admission functional status (as measured on the modified Barthel index), and urinary tract infection, but not with the use of anticholinergic medications. On discharge, 4 patients still had urinary retention (3 were voiding spontaneously and the other used intermittent catheterization). CONCLUSION: Urinary retention was common in patients with ischemic stroke. It should be strongly suspected in patients with aphasia, cognitive impairment, poor functional status, and diabetes mellitus.

Botulinum toxin A in the treatment of hemiplegic spastic foot drop--clinical and functional outcomes.

PURPOSE OF STUDY: This study investigated the effects of intramuscular Botulinum toxin A (BTX-A) in 7 ambulatory chronic hemiplegic subjects (5 male, 2 female) who had spastic hemiplegic foot drop. BASIC PROCEDURES: An open label study involving intramuscular injections of Botulinum toxin A (dilution 10 U/0.1 ml) was performed in ambulatory chronic hemiplegics. Tone as measured by the Modified Ashworth Scale (MAS), passive ankle joint range of motion (PROM), briskness of ankle reflexes, gait velocity, motor functional status and effects on the use of walking aids were measured at baseline, 3 and 12 weeks post-injection. MAIN FINDINGS: All subjects except I showed a significant decrease in MAS from 3.43 +/- 0.54 at baseline to 2.0 +/- 1.15 at 3 weeks post-injection, which was maintained during the 3 month study duration. The median change in PROM was 17.0 degrees (SD 12.1 degrees) at 3 weeks and 5.0 degrees (SD 7.1 degrees) at 12 weeks (p = 0.25) Gait velocity and Modified Barthel Index mobility scores which measured motor functional status were not significantly altered post-injection. The injections were generally well-tolerated and there were no serious adverse side effects. PRINCIPAL CONCLUSIONS: Although significant decreases in muscle tone were observed and maintained after intramuscular Botulinum toxin A during the 3 month study period, this regional intervention did not significantly influence functional status, gait velocity and the use of ambulatory aids.

Phenytoin-induced asterixis--uncommon or under-diagnozed?

Asterixis is a recognized but uncommon clinical sign of phenytoin toxicity. A case is presented in which asterixis and acute cerebellar dysfunction occurred when the phenytoin levels reached the toxic range. It disappeared when the drug levels normalized. Asterixis is now classified as a form of negative myoclonus, which is characterized by irregular myoclonic lapses of posture. The neurochemistry and physiology of phenytoin causing asterixis has yet to be elucidated.

Alcohol neurolysis of the sciatic nerve in the treatment of hemiplegic knee flexor spasticity: clinical outcomes.

OBJECTIVE: To study clinical outcomes after 50% to 100% alcohol neurolysis of the sciatic nerve in the treatment of chronic hemiplegic knee flexor spasticity. DESIGN: Case series using a convenience sample. SETTING: Rehabilitation teaching hospital. PATIENTS: Eight patients (mean age, 55.1 +/- 12.1 yr; mean duration to block, 4.4 +/- 3.7 mo) with chronic hemiplegia and severe spasticity (modified Ashworth scale [MAS] score < 2) secondary to cerebrovascular accidents (n = 5) and traumatic brain injuries (n = 3). Two patients were ambulant, 6 were wheelchair-bound. INTERVENTIONS: Fifty percent to 100% alcohol neurolysis of the sciatic nerve using repetitive electric stimulation to localize the sciatic nerve. MAIN OUTCOME MEASURES: MAS score, gain in knee range of motion (ROM), and visual inspection of gait at 0, 1, and 6 months postneurolysis. Nonparametric tests were used in statistical analysis. RESULTS: The mean preinjection MAS score was 2.8 +/- 0.7, which improved to 1.4 +/- 0.7 at 1 month (p = .005), and 1.8 +/- 0.9 (p = .01) and 1.9 +/- 1.1 (p = .02) at 3 and 6 months postinjection, respectively. The mean gain in knee ROM was 34.4 degrees +/- 15.7 degrees at 1 month postinjection and was maintained at 6 months postinjection. Improvements in gait were noted in both ambulant patients, and improved positioning in 3 of 6 wheelchair-bound patients. The incidence of dysesthetic pain was 0%. CONCLUSION: Fifty percent to 100% alcohol neurolysis of the sciatic nerve is a safe and effective method for treatment of hemiplegic knee flexor spasticity, with therapeutic effects lasting 6 months.

Expression and characterization of human tyrosinase from a bacterial expression system.

To carry out biochemical characterizations of human tyrosinase and to provide an unlimited source of the enzyme for further study, an expression plasmid, pHis-Tyrosinase, which contains the entire coding sequence except the signal sequence of a human tyrosinase was constructed and expressed in Escherichia coli. The expressed enzyme was simply purified by an immobilized metal affinity chromatography. The recombinant enzyme had the same electrophoretic mobility as the native enzyme from human melanoma cell and cross-reacted with the polyclonal antibody raised against the native enzyme. The recombinant enzyme retained its catalytic function with both hydroxylating and oxidative activities. Km values for L-tyrosine and L-3,4-dihydroxy-phenylalanine of the recombinant enzyme were 0.17 and 0.36 mM, respectively. The activity of the recombinant enzyme was optimal at pH 7.5. Glutathione notably inhibited the enzymatic activity. This work is a further enzymatic characterization of human tyrosinase.