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S S Ho

Publications and source records attributed to S S Ho.

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

Congenital porencephaly: MR features and relationship to hippocampal sclerosis.

PURPOSE: We determined the frequency of amygdalar-hippocampal atrophy in patients with congenital porencephaly-related seizure disorders to ascertain whether specific MR features of the porencephaly correlate with amygdalar-hippocampal atrophy and epilepsy. METHODS: We studied brain MR images of 22 patients with congenital porencephaly and measured the volume of the amygdala, the hippocampal formation, and the porencephalic cyst. We then compared imaging features with seizure symptoms. RESULTS: Porencephaly was unilateral in 20 patients and bilateral in two. Eighteen patients had cortical or subcortical cavitation and four had encephaloclastic changes (noncircumscribed parenchymal destruction associated with cystic components). The porencephaly was located in the middle cerebral artery territory in 12 patients, in the posterior cerebral artery in four, in the internal carotid artery in two, and in multiple vessels in four. The volume of the porencephalic cyst ranged from 1% to 32% of total intracranial volume (mean, 11%). Volumetry detected atrophy of the hippocampal formation in 21 cases (11 unilateral, 10 bilateral) and atrophy of the amygdala in 12 (nine unilateral, three bilateral). No correlation was found between size or location of the porencephaly and degree of hippocampal atrophy. Seizure symptoms correlated with mesial temporal origin but not with cyst location. CONCLUSION: Amygdalar-hippocampal atrophy often coexists with congenital porencephaly (95%), and the atrophy may be bilateral despite unilateral cysts. Hippocampal structures should be carefully assessed in patients with porencephaly-related seizures.

Adolescent↗
PubMed1997

Disappearing suprarenal masses in fetuses and infants.

This paper presents 12 infants (9 boys, 3 girls) in whom the diagnosis of a suprarenal mass (10 left, 2 bilateral) was made on antenatal sonography. All were otherwise healthy neonates who were born at term after a normal pregnancy, labor and delivery. The masses ranged from 1 to 3.5 cm in diameter on initial scans at gestational ages of 19-35 weeks. Eleven masses were hyperechoic and 4 of these contained small, well-defined cysts. The 12th was hypoechoic. Follow-up sonography showed complete disappearance of the mass antenatally in 1 case and postnatally by 4-6 months in 5 cases; there was marked diminution in the size of the mass by 2 months of age in 4 infants, by 4 months in 1 case and by 15 months in 1 case. Eleven were managed nonoperatively. Laparotomy (after disappearance of the mass) in the 12th case revealed only some fibrous tissue. The 11 echogenic masses resemble previously reported imaging findings in infants with histologically proven intra-abdominal sequestrated lung. Conservative management with careful sonographic follow-up should, therefore, be considered in otherwise healthy fetuses or neonates with these imaging findings. We are less certain what the hypoechoic mass represented.

Bronchopulmonary Sequestration↗
PubMed1997

Perfusion patterns during temporal lobe seizures: relationship to surgical outcome.

We sought to determine whether patterns of ictal hyperfusion demonstrated using [99mTC]HMPAO (hexamethylpropylene amine oxime) single photon emission computed tomography (SPECT) predict outcome of temporal lobectomy; in particular, whether the more extensive patterns of ictal hyperperfusion are associated with poor outcome. We studied 63 patients who had ictal SPECT studies prior to temporal lobectomy. Hyperperfusion on ictal SPECT scans was lateralized, and classified into: (i) 'typical', (ii) 'typical with posterior extension', (iii) 'bilateral' and (iv) 'atypical' patterns. Outcome (minimum of 2 years follow-up) was classified as either seizure free, or not seizure free. Actuarial analysis was used to test the relationship of SPECT patterns with outcome. There were 35 cases with the typical ictal SPECT pattern, 13 posterior, nine bilateral and six atypical cases. The atypical pattern was associated with lack of pathology in the surgical specimen. Outcome was similar for the typical, posterior and bilateral with 60%, 69% and 67% seizure free, respectively. In contrast, the atypical group had a worse outcome with only 33% seizure free. Actuarial analysis showed a significant difference in outcome between patients with the typical pattern, and patients with the atypical pattern (P = 0.04). We conclude that extended patterns of ictal perfusion in temporal lobe epilepsy do not predict poor outcome, indicating that extended hyperperfusion probably represents seizure propagation pathways rather than intrinsically epileptogenic tissue. Atypical patterns of hyperperfusion are associated with poor outcome and may indicate diffuse or extra-temporal epileptogenicity.

Actuarial Analysis↗
PubMed1997

Algorithm on the clinical evaluation of epilepsy.

Epilepsy is an important public health problem because of its prevalence in the community and the economic disadvantage associated with its chronic morbidity. Uncontrolled seizures are potentially life-threatening and have adverse psychosocial consequences. Surgery is an effective but underutilized therapy for some patients with medically refractory seizures. However, this form of treatment demands precise localization of the epileptogenic zone. In recent years there have been major advances in the development of various imaging techniques for seizure localization. The best combination of diagnostic testing with regard to cost-benefit has been debated. A rational strategy for the deployment of these techniques is discussed.

Algorithms↗
PubMed1997

Congenital porencephaly and hippocampal sclerosis. Clinical features and epileptic spectrum.

We studied clinical features and seizure localization in 14 patients with porencephaly and intractable seizures. Perinatal complications were present in nine patients, childhood febrile convulsions in two, congenital hemiparesis in 12, and intellectual impairment in seven. Ten patients had psychoparetic complex partial seizures (CPS), three had sensorimotor simple partial seizures, and one had generalized tonic-clonic seizures. Surface EEG showed temporal onset in nine patients (one bitemporal) and extratemporal onset in four. MRI showed porencephaly in the distribution of the middle cerebral artery in eight patients, posterior cerebral in three, internal carotid in one, and multiple vessels in two. MR-based volumetry revealed hippocampal formation atrophy in 13 patients (eight unilateral and five bilateral) and amygdalar atrophy in 10 patients (nine unilateral and one bilateral). Hippocampal formation atrophy was concordant with CPS semiology in 10 patients (71%) and with EEG temporal localization in nine patients. Two patients had pathologic confirmation of mesial temporal sclerosis and were seizure free after temporal lobectomy. We conclude that mesial temporal sclerosis often coexists with porencephaly and is the likely seizure focus in the presence of concordant electroclinical data. This recognition implies that effective surgical intervention can be offered to certain patients with porencephaly-related seizure disorders. The dual pathology and association with perinatal cerebral vascular occlusion suggest a common ischemic pathogenesis.

Adolescent↗
PubMed1996

Gene expression of interleukin-3 and granulocyte macrophage colony-stimulating factor in circulating CD4+ T cells in acute severe asthma.

BACKGROUND: Interleukin (IL)-3 and granulocyte macrophage colony-stimulating factor (GM-CSF) may influence the inflammatory process in asthma through their regulatory role on eosinophil survival, differentiation and effector function. OBJECTIVE: To examine the relationships between IL-3 and GM-CSF messenger (m) ribonucleic acid (RNA) expression in peripheral blood CD4+ cells and serum levels of eosinophil cationic protein (ECP), a marker of eosinophil activation, and disease activity in asthma. METHODS: Venous blood was drawn from patients with acute severe asthma prior to the commencement of systemic steroid therapy (day 1) and 7 days afterwards (day 7), patients with stable disease and normal healthy volunteers. The capacity for expression of IL-3 and GM-CSF in ex vivo stimulated circulating CD4+ cells was assessed semi-quantitatively by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: We found that the capacity for expression of IL-3 and GM-CSF was significantly higher in acute asthmatics prior to steroid treatment (n = 24) than those in stable disease (n = 38) and healthy subjects (n = 32, P < 0.001 for IL-3 and < 0.05 for GM-CSF), but no difference was observed between the latter two groups. Further assessment made in 15 of the 24 acute asthmatics 7 days after systemic steroid treatment revealed a significant reduction in GM-CSF expression (P < 0.05) but not for IL-3. At the same time, PEF also improved significantly from 30.4 +/- 3.5% of predicted value to 72.9 +/- 7.2% (P < 0.0001) and serum ECP concentration also fell from 19.9 +/- 5.9 micrograms/L to 4.3 +/- 2.0 micrograms/L (n = 10, P < 0.01). CONCLUSION: Our data suggest both IL-3 and GM-CSF may be important in the pathogenesis of acute severe asthma.

Acute Disease↗
PubMed1996

Temporal lobe epilepsy subtypes: differential patterns of cerebral perfusion on ictal SPECT.

PURPOSE: We studied cerebral perfusion patterns in the various subtypes of TLE, as determined by pathology and good outcome after temporal lobectomy (as confirmation of temporal origin). METHODS: We studied clinical features and ictal technetium 99m hexamethyl-propyleneamineoxime (99mTc-HM-PAO) single-photon emission-computed tomography (SPECT) in four subgroups of patients with intractable temporal lobe epilepsy (TLE) treated with surgery: hippocampal sclerosis (group 1, n = 10), foreign-tissue lesion in mesial temporal lobe (group 2, n = 8), foreign-tissue lesion in lateral temporal lobe (group 3, n = 7), and normal temporal lobe tissue with good surgical outcome (group 4, n = 5). RESULTS: No major clinical differences in auras, complex partial seizures or postictal states were identified among the groups. Ictal SPECT showed distinct patterns of cerebral perfusion in these subtypes of TLE. In groups 1 and 2, hyperperfusion was seen in the ipsilateral mesial and lateral temporal regions. In group 3, hyperperfusion was seen bilaterally in the temporal lobes with predominant changes in the region of the lesion. Hyperperfusion was restricted to the ipsilateral anteromesial temporal region in group 4. Ipsilateral temporal hyperperfusion in mesial onset seizures can be explained by known anatomic projections between mesial structures and ipsilateral temporal neocortex. Bilateral temporal hyperperfusion in lateral onset seizures can be explained by the presence of anterior commissural connections between lateral temporal neocortex and the contralateral amygdala. CONCLUSIONS: We conclude that the perfusion patterns seen on ictal SPECT are helpful for subclassification of temporal lobe seizures, whereas clinical features are relatively unhelpful. These perfusion patterns provide an insight into preferential pathways of seizure propagation in the subtypes of TLE.

Adolescent↗
PubMed1995

Comparison of ictal SPECT and interictal PET in the presurgical evaluation of temporal lobe epilepsy.

We retrospectively compared ictal technetium 99m hexamethylpropyleneamineoxime single-photon emission computed tomography (SPECT) and interictal 18F-fluorodeoxyglucose positron emission tomography (PET) in 35 patients with well-lateralized temporal lobe epilepsy (TLE). Based on SPECT scans the two observers correctly lateralized seizure foci with certainty in 89% of patients; interobserver agreement was excellent. Both observers incorrectly lateralized the seizure focus on two SPECT scans; one error was explained by rapid electroencephalographic spread to the contralateral side and for the other patient, isotope was injected during a brief aura. Based on PET scans, observers correctly lateralized the foci with certainty in 63% and with lesser confidence in 83%; four incorrect lateralizations were made by one observer and none by the other. PET interobserver disagreement was explained by differences between observers in weighting the relative hypometabolism in medial and lateral temporal regions. The detection rate for PET was lower in the absence of structural imaging abnormalities (60 vs 87%). PET yielded correct lateralizations in the 2 patients for whom SPECT interpretation was difficult. We conclude that both ictal SPECT and interictal PET are sensitive methods for the lateralization of TLE, but SPECT can be interpreted with greater certainty and is more sensitive when magnetic resonance imaging findings are negative. False lateralization is rare with ictal SPECT and can be explained when interpreted in conjunction with electroclinical data. Both investigations have complementary roles when localization is difficult.

Adolescent↗
PubMed1995

Respiratory symptoms in elderly Chinese living in Hong Kong.

Respiratory diseases can cause considerable disability in the elderly because of their limited respiratory reserve as a result of ageing. We have investigated the prevalence of respiratory symptoms and diseases in elderly Chinese in Hong Kong and compared these data with those in elderly Caucasian populations. Two thousand and thirty two (999 male and 1,033 female) subjects, selected by age-stratified random sampling from a register of Hong Kong residents aged 70 yrs and over were interviewed to complete a respiratory questionnaire. Total serum immunoglobulin E (IgE) was measured in 195 subjects. At least one respiratory symptom was reported by 56% of subjects. The most frequently reported symptoms were morning phlegm (26%), chronic cough with phlegm (10%) and wheeze in the past 12 months (8%). Of the self-reported diseases, the commonest was chronic bronchitis (7%), followed by asthma (5%), pulmonary tuberculosis (3%) and emphysema (2%). Of the 218 subjects with obstructive airway diseases, 128 (59%) had sought medical advice in the past 12 months. The most important determinants for respiratory symptoms and diseases were smoking and social class. Total serum IgE was significantly higher in current smokers than nonsmokers and also in those with chronic cough and phlegm than those without these complaints. Our study shows that respiratory ailments in Hong Kong elderly are as common as those reported in Sweden and the USA but less than those in England.

Aged↗
PubMed1995

Inhaled salmeterol and albuterol in asthmatic patients receiving high-dose inhaled corticosteroids.

Salmeterol may be useful in the treatment of asthmatic patients requiring high-dose inhaled steroids, and there have been debates about its anti-inflammatory action. We have compared the efficacy and effects on serum inflammatory markers, including soluble interleukin 2R (sIL-2R), eosinophil cationic protein (ECP), and tryptase of salmeterol and albuterol in 20 patients with moderate to severe asthma who were all receiving high-dose inhaled corticosteroids and inhaled beta 2-agonist on demand. After a 2-week run-in period, they received, in a randomized, crossover, double-blind and placebo-controlled manner, either salmeterol, 50 micrograms twice a day, or albuterol 400 micrograms, four times a day, from a powder inhaler during two 2-week treatment periods, separated by a 2-week washout. Compared with albuterol, salmeterol treatment was associated with better morning and mean peak expiratory flow (p = 0.013 and 0.016, respectively), less daytime and nocturnal symptoms (p = 0.008 and 0.01, respectively), reduced requirement of rescue albuterol (p = 0.04), and better efficacy rating by patients (p = 0.04). However, serum concentration of sIL-2R was significantly higher during regular albuterol treatment (p = 0.014) but no differences were seen in the concentrations of ECP and tryptase between the two treatment periods. We conclude that inhaled salmeterol, 50 micrograms twice daily, confers a better control of asthma than albuterol, 400 micrograms four times daily, in patients with moderate to severe disease, and the latter treatment may be associated with increased T-lymphocyte activation.

Administration, Inhalation↗
PubMed1994

Differential expression of activation markers during tolerance induction by superantigens in T-cell receptor (beta-chain) transgenic mice.

To investigate the process of tolerance induction we have developed an in vivo model using TCR beta-chain transgenic mice tolerized with the superantigen staphylococcal enterotoxin B. We have previously demonstrated that tolerized peripheral T cells were anergic when stimulated in vitro with immunogenic peptides, superantigens, mitogens, and immobilized anti-TCR mAb. However, the development of anergy is preceded by an induction phase which produces expansion followed by contraction of the peripheral T cell population presumably due to proliferation and programmed cell death, respectively. The current experiments focus on the induction phase of tolerance. A kinetic functional analysis showed that the inhibition of proliferation was apparent 2-3 days post-tolerization. Interestingly, the inhibition of proliferation correlated with the loss of IL-2R alpha expression, which occurred 2 days post-tolerization following an initial increase in IL-2R alpha expression. In addition, the expression of multiple activation markers including CD44, Ly-6A/E, and very early activation marker H1.2F3 is induced, whereas the expression of CD45RB is decreased during tolerance induction. Elevated expression of Ly-6A/E persists up to 28 days post-tolerization; however, altered expression of the other markers does not persist and near baseline levels of the other markers are noted 7 to 28 days post-tolerization. These results show that tolerance induction is an active process which has functional and phenotypic similarities to antigen-specific immunity. However, tolerance induction in our system differs from immunity in terms of the early loss of IL-2R alpha expression, the persistent increased expression of Ly-6A/E, and the lack of development of CD45RBlo memory-type T cells.

Animals↗
PubMed1994

Parietal lobe epilepsy: clinical features and seizure localization by ictal SPECT.

We studied clinical and ictal single-photon emission computed tomography (SPECT) features in 14 patients with parietal lobe epilepsy, nine of whom had structural parietal lobe lesions. Thirteen patients had simple partial seizures of somatosensory (eight), psychic (four), and motor (nine) types. Complex partial seizures (CPS) occurred in seven patients; six were psychoparetic (prominent staring, relative immobility) and one had hyperkinetic activity. Seizures lasted 7 to 110 seconds; 99mTc-HMPAO (hexamethylpropylene amine oxime) was injected ictally, 7 to 89 seconds from seizure onset and 0 to 74 seconds (mean, 21.0 +/- 24.4 seconds) before seizure termination. Ictal SPECT demonstrated focal areas of parietal hyperperfusion in all 14 cases and corresponded with sites of the structural lesions. Parietal hyperperfusion was anterior in eight, posterior in four, and diffuse in two. Quantitative analysis revealed increases in parietal side-to-side perfusion ratios on ictal compared with interictal scans of 11 to 51% (mean, 25.5 +/- 14.4%). Ictal SPECT localization correlated with two main clinical seizure patterns: an anterior syndrome characterized by sensorimotor manifestations and a posterior syndrome characterized by CPS of the psychoparetic type. Ictal SPECT is helpful for localization of parietal seizures. Parietal hyperperfusion is discrete and short-lived, demanding true ictal injections for diagnostic studies.

Adolescent↗
PubMed1993

Superantigen-induced peripheral tolerance inhibits T cell responses to immunogenic peptides in TCR (beta-chain) transgenic mice.

TCR (beta-chain) transgenic mice were tolerized with the superantigen staphylococcal enterotoxin B (SEB). Three to 28 days after tolerization with SEB, flow cytometry of peripheral T cells showed the persistence of SEB-unresponsive T cells that did not express reduced levels of the TCR (beta-chain) transgene. Stimulation of the tolerized T cells with a panel of superantigens (SEC1), mitogens (Con A, PHA, and pertussis toxin) and mAb (anti-CD3 epsilon) did not induce T cell proliferation. In contrast to other models, exogenous rIL-2 did not reverse unresponsiveness and induce proliferation. In addition, lymphokines rIL-4 and rIL-6 also did not induce proliferation. However, the unresponsive T cells did respond to the combination of PMA plus ionomycin, but not to PMA or ionomycin alone. Thus, the block in signal transduction in the anergic state occurs between the stimulation of cell surface receptors and the activation of protein kinase C and the increase in intracellular calcium. In addition, these results show that mature T cells tolerized with the superantigen SEB are unresponsive to a wide array of T cell stimuli, indicating a block in a common signal transduction pathway.

Animals↗
PubMed1993

Circulating adhesion molecules in tuberculosis.

Leucocyte-endothelial adhesion molecules have been implicated in the pathogenesis of inflammatory diseases. To evaluate their role as markers of disease activity in tuberculosis, we have used an antigen capture ELISA to measure the serum concentrations of circulating intercellular adhesion molecule-1 (cICAM-1), E-selectin (cE-selectin) and vascular cell adhesion molecule-1 (cVCAM-1) in 34 patients with active tuberculosis (27 with pulmonary disease and seven with lymph node disease) before the commencement of standard chemotherapy, 15 subjects who had previously completed treatment for pulmonary tuberculosis, and 27 healthy volunteers. Circulating ICAM-1 and E-selectin levels were significantly elevated in patients with active tuberculosis when compared to those with treated disease (P < or = 0.01), and healthy controls (P < 0.02). Circulating VCAM-1 was raised in patients with active or old pulmonary tuberculosis (P < 0.02 versus healthy controls) but not in those with tuberculous lymphadenitis. Significant correlations were observed between the levels of cICAM-1 and cE-selectin (p = 0.63, P = 0.0001), and between cICAM-1 and cVCAM-1 (p = 0.28, P = 0.016). Taking the mean +2 s.d. of the serum level in healthy controls as the upper limit of normal range, circulating ICAM-1 had the best discriminative power in identifying active tuberculosis, being elevated in about 80% of patients but was raised in only 6.7% of subjects with treated disease and in 3.7% of normal subjects. Our data support the possibility that three adhesion molecules may be involved in the pathogenesis of tuberculosis and cICAM-1 may be a useful marker of disease activity.

Adolescent↗