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Biomedical subjects

K H Kong

Publications and source records attributed to K H Kong.

At least 37 records · Page 2Linked to original sources
PubMed1998

Central cord syndrome: functional outcome after rehabilitation.

Seventy-three spinal cord injured patients with central cord syndrome who had undergone inpatient rehabilitation, were studied retrospectively with regard to their demographic, neurologic and functional characteristics. There were 67 males and six females with a mean age of 53.5 years. Falls was the commonest mechanism of injury (54.8%) followed by motor vehicle accidents. Eleven patients sustained cervical fractures and 41 had radiological evidence of cervical spondylosis. Seventeen patients had sensory impairment and significant spasticity was present in 14 patients. Significant improvements in the admission/discharge ASIA motor scores and Modified Barthel Index (MBI) scores (P < 0.001) were noted after rehabilitation. Ninety-two percent of patients were continent of bladder on discharge compared to 64.4% on admission. Multiple regression analysis revealed three factors associated with a better functional outcome, namely, higher admission MBI scores, absence of spasticity and younger age (P < 0.05).

Adult↗
PubMed1998

Purification and characterization of the tyrosinase isozymes of pine needles.

Three tyrosinase isozymes were purified to electrophoretic homogeneity from pine needles. The molecular weight of the three isozymes (P1, P2 and P3) were approximately 65,000, 50,000 and 45,000, and the pI values were 6.2, 5.9 and 5.3, respectively. The three isozymes have a number of common properties. These include amino acid composition, substrate specificity, response to inhibition. The amino acid compositions of the three isozymes showed the characteristic high contents of glycine, serine and glutamic acid residues. The three isozymes exhibited high substrate specificity towards pyrogallol. The K(m) values of the three isozymes for L-DOPA ranged from 8.7 to 10 mM. L-ascorbic acid and beta -mercaptoethanol, glutathione and sodium diethyldithiocarbamate notably inhibited the enzymatic activities.

Amino Acids↗
PubMed1997

Functional analysis of the evolutionary conserved arginine 182 residue in human glutathione S-transferase P1-1.

The mutational replacement of Arg182 with threonine markedly decreased the specific activities for GSH-conjugation reaction. The Kcat of R182T for GSH-[1-chloro-2,4-dinitrobenzene] conjugation reaction was about 100-fold smaller than that of the wild type. On the other hand, the affinity for GSH of R182T was not significantly affected. The pKa of the thiol group of GSH bound in R182T was approximately 0.9 pK units higher than those in the wild type, but the Kcat/Km1-chloro-2,4-dinitrobenzene values at high pH were not so much lower than those of the wild type. The thermostability of R182T was significantly lower than that of the wild type. Therefore, Arg182 seems to be important for the construction of the active enzyme structure.

Amino Acid Sequence↗
PubMed1996

Heterologous expression and site-directed mutagenesis studies on the activation mechanism and the roles of the basic residues in the prosegment of aspergillopepsinogen I.

To study the structure/function relationship of the prosegment of aspartic proteinase, a putative proform of aspergillopepsin I (or proteinase B) from Aspergillus niger var. macrosporus was expressed by Escherichia coli, refolded in vitro, and purified. The conversion of the purified proenzyme (aspergillopepsinogen I, proproteinase B) into the active mature form occurred at pH < or = 4.5 and was completely inhibited by pepstatin A, a specific inhibitor for aspartic proteinase, suggesting autoprocessing. The N-terminus of this mature form was Glu67 (numbering in preproform), which was different from the N-terminal Ser70 of native proteinase B although there was no significant difference in enzymatic activity. During the conversion, two intermediates were observed on SDS/PAGE, indicating a stepwise mechanism. The Lys56-Phe57 sequence seems to be a counterpart of the Lys-Tyr pair highly conserved in the prosequences of aspartic proteinases. When the mutant proenzyme (K56N), in which Lys56 was replaced with Asn by site-directed mutagenesis, was allowed to refold under various conditions, no significant potential activity could be obtained. Proproteinase B was also expressed by Bacillus brevis HPD31. This system required no in vitro refolding to obtain potentially active proenzyme, which was secreted into the culture medium (30-120 mg/l) and had the same properties with that obtained by the E. coli system. The K56N mutant prepared by this system also had no potential activity, and was rapidly digested by incubation with native proteinase B, suggesting that the mutant did not fold correctly. On the other hand, the K56R mutant (Lys56-Arg) was potentially active. These results indicated that Lys56 is essential for the folding through electrostatic interaction with the catalytic Asp residues in the active site although it may be replaced with Arg. In the presence of a low concentration of pepstatin A, an incompletely processed form with N-terminal Ser53 was obtained. Further, the R52Q (Arg52-->Glin) mutant showed no processing but was converted to the active mature form by incubation with the native enzyme. Therefore, the cleavage between Arg52 and Ser53 is considered to be the initial and essential step of the autoactivation. The R26Q, K27Q, R36Q, K40Q, R42Q, and K66Q mutants were also potentially active. The K66Q mutant was processed to a form with N-terminal Ala55.

Amino Acid Sequence↗
PubMed1996

Carbamazepine-induced hepatitis in a patient with cervical myelopathy.

Carbamazepine is a drug commonly used in the treatment of neuropathic pain. It is an iminostilbene derivative that is extensively metabolized by the liver. We describe a 66-year-old man with dysesthetic pain from cervical myelopathy who developed cholestatic hepatitis, skin rash, and eosinophilia after carbamazepine was administered for 5 weeks (total dose of 18.9gm). Withdrawal of carbamazepine led to complete resolution of both clinical and biochemical abnormalities within 3 weeks. Clinicians should be alert to this rare complication because it can be confused clinically with biliary tract sepsis and viral hepatitis.

Aged↗
PubMed1996

Functional outcome in brain stem stroke patients after rehabilitation.

OBJECTIVE: To document functional outcome before and after rehabilitation in a group of brain stem stroke patients and to analyze possible factors influencing outcome. DESIGN AND SETTING: A case series of 53 consecutive inpatients admitted to a rehabilitation facility with confirmed brain stem strokes over a period of 6 years. PATIENTS AND OUTCOME MEASURES: Patients were selected by physiatrists for admission into the rehabilitation program. Outcome was measured by the Modified Barthel Index (MBI) for mobility and activities of daily living. RESULTS: The mean age of this cohort was 57.9 +/- 11.9 years and the pons was involved in 55% of cases. Ataxia (68%) and hemiplegia (70%) were the most frequent neurological deficits. Twenty-one patients (40%) had significant dysphagia with risk of aspirin and 16 patients (30%) were incontinent of urine. Aspiration pneumonia and urinary tract infection were present in 8 (15%) and 13 (25%) patients, respectively. Significant improvements in functional status, motor strength, swallowing, and continence status were documented on discharge (p < .05). The total admission MBI was the only significant factor influencing total discharge Barthel Index ( Beta = .597, adjusted R2 = .476, p < .0001). Fifty-one (96%) were discharged home after rehabilitation. CONCLUSIONS: Despite multiple physical deficits, this cohort of brain stem stroke patients made functional gains during rehabilitation with significant improvements in mobility and self-care skills, motor strength, severity of ataxia, continence and swallowing status.

Activities of Daily Living↗
PubMed1995

Ruptured intracranial mycotic aneurysm: a rare cause of intracranial hemorrhage.

Intracranial mycotic aneurysm is a rare complication in patients with infective endocarditis occurring in about 2% to 10% of cases. Although the risk of rupture is about 1.7%, it is usually a catastrophic event with a fatality rate of 80%. Neurological deficits secondary to cortical involvement are common, given the frequency of intralobar hemorrhage. We report two cases of intracerebral hemorrhage caused by ruptured intracranial mycotic aneurysms. Both had involvement of the right frontoparietal lobes with resultant left hemiparesis, left homonymous hemianopia, and impairments of cognition and perceptual function. Despite intensive rehabilitation, their functional outcomes were less than satisfactory as they needed assistance in self-care activities and mobility on discharge.

Adult↗
PubMed1995

"Great mimicry" in a patient with tetraparesis: a case report.

The patient is a 63-year-old Chinese man who presented with tetraparesis and urinary incontinence. The initial diagnosis was cord compression from cervical spondylosis. The patient relapsed 3 months after cervical laminectomy. The transverse myelitis picture, left optic atrophy and suggestive brainstem evoked potentials led to treatment of a presumptive demyelinating process. The presence of vitiligo, however, led to detection of high titers of antinuclear antibodies (ANA) and presence of anti-nonhistone antibodies. The patient was then diagnosed to have a lupus (SLE)-like disease, which has not fully evolved. He was prescribed pulsed cyclophosphamide and prednisolone with significant gains both neurologically and functionally up to 1 year of follow-up. This report highlights the befuddling impact the disease process have on the clinicians in terms of diagnosis, treatment, and prognosis. That it can occur in men in the seventh decade of life heightens the need for awareness in our approach to the myelopathic patient.

Cervical Vertebrae↗
PubMed1995

Prolonged fever and heterotopic ossification in a C4 tetraplegic patient. Case report.

Prolonged fever is an uncommon diagnostic problem in a spinal cord injury patient. The underlying causes include recurrent infections, thromboembolic phenomena and central fever. We report a case of heterotopic ossification in a traumatic C4 tetraplegic patient presenting as prolonged fever of 3 months' duration. Treatment with oral indomethacin led to prompt resolution of the fever and acute manifestations of heterotopic ossification. The efficacy of indomethacin in the treatment of heterotopic ossification in spinal cord injury needs to be further confirmed in larger studies.

Adult↗
PubMed1995

Paroxysmal hypertension in a C4 spinal cord injury--a case report.

Hypertension in a patient with acute spinal cord injury is commonly caused by autonomic dysreflexia, which is a syndrome of paroxysmal hypertension associated with headaches, relative bradycardia and vasomotor instability secondary to sympathetic overactivity. Life-threatening complications such as seizures and intracerebral haemorrhage are largely preventable. We report both acute and chronic forms of autonomic dysreflexia due to underlying urinary and faecal impaction in a 33-year-old female with traumatic C4 quadriplegia. She was successfully managed with a combination of physical and pharmacological measures including calcium channel and sympathetic blockers.

Adult↗
PubMed1995

Functional outcome in young strokes.

Fifty-seven young stroke patients (aged 45 years and below) admitted to a rehabilitation centre were assessed for underlying risk factor/aetiology and functional outcome after rehabilitation. The mean age was 37.2 +/- 6.3 years and the mean length of stay in the rehabilitation ward 38.3 +/- 19.9 days. There were 37 (64.9%) haemorrhagic and 20 (35.1%) ischaemic strokes. Hypertension was the single most important risk factor accounting for 49.1% of all strokes. Vascular abnormalities (arteriovenous malformation, mycotic aneurysm, vasculitis and Moya-moya disease) and cardiogenic embolism secondary to rheumatic valvular heart disease were also significant causes. There was significant improvement in functional status--activities of daily living (ADL) and mobility--after rehabilitation, the mean Functional Status score improving from 9.76 +/- 2.2 on admission to 5.07 +/- 1.95 on discharge (P < 0.01). Higher ADL and mobility function and upper and lower limb motor power of grade 3 and above on admission, absence of dysphasia, left hemiplegia, age less than 40 years and rehabilitation stay of less than 28 days were associated with better functional outcome whilst sex, nature and site of stroke, and length of stay in the acute ward had no significant bearing.

Activities of Daily Living↗
PubMed1994

Molecular cloning and site-directed mutagenesis of glutathione S-transferase from Escherichia coli. The conserved tyrosyl residue near the N terminus is not essential for catalysis.

Glutathione S-transferase (GST) was purified from Escherichia coli K-12, and its N-terminal sequence was determined to be MKLFYKPGAXSLAS. The gene encoding this sequence was cloned and mapped at 1731-1732 kilobases on the E. coli gene map. It encoded a polypeptide of 201 amino acid residues with a calculated molecular weight of 22,860. The overexpressed product of the gene was confirmed to have GST activity toward 1-chloro-2,4-dinitrobenzene and ethacrynic acid and GSH-dependent peroxidase activity toward cumene hydroperoxide. The relative molecular mass of the gene product was determined to be 40,000 by gel chromatography and 25,000 by SDS-polyacrylamide gel electrophoresis, indicating a homodimeric structure. The deduced amino acid sequence was 54% identical with that of Proteus mirabilis GST. Although the homologies between the GSTs from E. coli and mammals were low, many of the residues assigned to be important for the enzymatic function or structure in mammalian cytosolic GSTs were found to be conserved in E. coli GST. Therefore, E. coli GST is considered to have diverged from the same ancestor with other cytosolic GSTs. A specific tyrosyl residue in the vicinity of the N terminus is conserved in all of the known cytosolic GSTs and has been shown to function as a catalytic residue in alpha, mu, and pi class GSTs from mammals. Although Tyr5 in E. coli GST appeared to be the counterpart of the catalytic residue, its replacement with phenylalanine did not significantly affect the enzymatic activity. Therefore, this apparently conserved tyrosyl residue is not essential for catalytic activity in E. coli GST.

Amino Acid Sequence↗
PubMed1994

Detrusor hyperreflexia in strokes.

Urodynamic evaluation via water cystometry was undertaken in 27 patients from 12 to 120 days after cerebrovascular accidents. Seven patients had urinary symptoms--five with urge incontinence, one with frequency and one with sensation of incomplete bladder emptying. The remaining 20 were asymptomatic. Cystometry revealed normal bladder function in 15 patients (55.6%), detrusor areflexia in one patient (3.7%) and detrusor hyperreflexia in 11 patients (40.7%). Of the 11 patients with detrusor hyperreflexia, six (54.5%) were asymptomatic and the remaining five (45.5%) had urge incontinence. The former group had a statistically significant higher first sensation and functional cystometric capacity than the latter. Urge incontinence was also found to be an accurate predictor of detrusor hyperreflexia.

Adult↗
PubMed1994

Reflex sympathetic dystrophy in hemiplegia--two case reports and review of the literature.

Reflex sympathetic dystrophy (RSD) can be precipitated by a variety of events. We report two cases of RSD in hemiplegic patients detected within three months of the cerebrovascular accidents. Diagnosis of RSD was based upon clinical and scintigraphic findings. Management included elevation, range of movement of the affected joints and analgesics. With treatment, the pain and swelling subsided, range of motion of joints improved and the patients were able to participate in the rehabilitation programme. A high index of suspicion, early diagnosis and aggressive treatment were found to be essential for the successful treatment of RSD.

Cerebral Hemorrhage↗
PubMed1993

Seroepidemiology of hepatitis A and hepatitis B virus infection in a Gurkha community in Singapore.

The overall prevalence of hepatitis A virus (HAV) infection among the Gurkhas and their families stationed in Singapore was 83.2%, with antibody to HAV detected in 67 (38.1%) of 176 children under 5 years of age, 121 (76.6%) of 158 children between 5 and 14 years, and 600 (97.9%) of 613 older children and adults over age 15 years. Children born in Singapore (102/223 or 45.7%) had a significantly lower crude prevalence than those born in Nepal (85/110 or 77.3%) (P < 0.000001). The age-adjusted difference in prevalence was also statistically significant (P < 0.001). Susceptible children had a high risk of acquiring HAV infection when they travelled to Nepal. As for hepatitis B virus (HBV) infection, the prevalence of hepatitis B surface antigen (HBsAg) was 2.8%, with a higher rate in males (20/560 or 3.6%) than in females (6/384 or 1.6%). The highest HBsAg prevalence (4/26 or 15.4%) was in young adult Gurkhas 15-19 years of age. No significant difference in the crude prevalence of HBV markers was noted between children born in Singapore (45/224 or 20.1%) and those born in Nepal (19/107 or 17.8%). Even after age adjustment, the difference remained insignificant. The prevalence of HBV markers of children of seropositive parents (27/156 or 17.3%) was not significantly higher than that of seronegative parents (19/131 or 14.5%). Married men had a significantly higher age-adjusted prevalence of infection than unmarried men (45.4% and 32.4%, respectively; P < 0.05). Seropositivity of one spouse was significantly correlated with the seropositivity of the other (P < 0.05), suggesting a role for heterosexual transmission of HBV infection.

Adolescent↗
PubMed1993

Site-directed mutagenesis study on the roles of evolutionally conserved aspartic acid residues in human glutathione S-transferase P1-1.

The evolutionally conserved aspartyl residues (Asp57, Asp98 and Asp152) in human glutathione S-transferase P1-1 were replaced with alanine by site-directed mutagenesis to obtain the mutants (D57A, D98A and D152A). The replacement of Asp98 with alanine resulted in a decrease of the affinity for S-hexyl-GSH-agarose, a 5.5-fold increase of the KmGSH and a 2.9-fold increase of the I50 of S-hexyl-GSH for GSH-CDNB conjugation. Asp98 seems to participate in the binding of GSH through hydrogen bonding with the alpha-carboxylate of the gamma-glutamyl residue of GSH. The kcat of D98A was 2.6-fold smaller than that of the wild-type, and the pKa of the thiol group of GSH bound in D98A was approximately 0.8 pK units higher than those in the wild-type. Asp98 also seems to contribute to the activation of GSH to some extent. On the other hand, most of the kinetic parameters of D57A and D152A were similar to those of the wild-type. However, the thermostabilities of D57A and D152A were significantly lower than that of the wild-type. Asp57 and Asp152 seem to be important for maintaining the proper conformation of the enzyme.

Amino Acid Sequence↗
PubMed1992

Tyrosine-7 in human class Pi glutathione S-transferase is important for lowering the pKa of the thiol group of glutathione in the enzyme-glutathione complex.

Previously, we reported the importance of Tyr7 for the catalytic activity of human class Pi glutathione S-transferase [Kong et al. (1992) Biochem. Biophys. Res. Comm., 182, 1122]. As an extension of this study, we investigated the pH dependence of kinetic parameters of the wild-type enzyme and the Y7F mutant. The replacement of Tyr7 with phenylalanine was found to alter the pH dependence of Vmax and Vmax/KmCDNB of the enzyme for conjugation of GSH with 1-chloro-2,4-dinitrobenzene (CDNB). The pKa of the thiol of GSH in the wild-type enzyme-GSH complex was estimated to be about 2.4 pK units lower than that in the Y7F-GSH complex. Tyr7 is thus considered to be important for catalytic activity in lowering the pKa of the thiol of GSH in the enzyme-GSH complex.

Amino Acid Sequence↗