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Biomedical subjects

S M Lai

Publications and source records attributed to S M Lai.

51 records · Page 3Linked to original sources
PubMed1990

Duplex Doppler and spectral flow analysis of racial differences in cerebrovascular atherosclerosis.

We compared carotid artery disease in 99 black and 106 white patients using duplex ultrasonography (B-mode imaging and Doppler spectral analysis). Blacks had significantly less stenosis of the extracranial internal carotid artery than whites. Among the risk factors investigated, hypertension alone, ischemic heart disease, diabetes mellitus, and smoking failed to explain the racial difference. Although carotid stenosis of greater than or equal to 40% correlated significantly with age in both races (p = 0.001 in whites and p = 0.005 in blacks), blacks had significantly less carotid stenosis of any degree even when age was taken into account. Multivariate analysis showed that race is a significant and independent risk factor for carotid stenosis (p less than 0.0001). Hypertension interacting with race was also significant. Our results require verification in population-based studies. Carotid duplex ultrasonography offers a noninvasive method for carrying out such studies.

Age Factors↗
PubMed1990

Idiopathic hypothalamic hypogonadism with polyostotic fibrous dysplasia: report of a case.

A 48-year-old man with Albright's syndrome and hypogonadism is presented. Eunuchoid status, hypogenitalia and hypogonadotropinemia were associated with pathological fracture and deformity of bones. GnRH test revealed minimal LH response and delayed FSH peak. After pulsatile GnRH priming, the LH response to GnRH increased. Results of other provocative hypothalamic-pituitary tests were consistent with hypothalamic lesions. To the best of our knowledge, this is the first report of a male patient with Albright's syndrome and idiopathic hypothalamic hypogonadism. The hypothesis of endocrinopathy and its relation to other components of this syndrome were reviewed.

Fibrous Dysplasia, Polyostotic↗
PubMed1990

Sonographic presentation in autoimmune thyroiditis.

We used real-time ultrasonography to examine 60 patients with autoimmune thyroiditis, then correlated the ultrasonic pictures with thyroid function, thyroid autoantibodies and fine needle aspiration cytology. In these 60 patients, 45 (75%) showed diffuse goiter, 6 (10%) showed multinodular goiter, and 9 (15%) had a solitary thyroid nodule sonographically. One of the 9 patients with a solitary nodule was a case of autoimmune thyroiditis combined with papillary carcinoma. The echogenicity of the thyroid was more than, the same as, or less than that of the adjacent muscles in 17, 22, and 21 patients, respectively. The groups were classified as hyperechoic, isoechoic, and hypoechoic, respectively. The mean serum T4 level was significantly lower in the hypoechoic group than in the hyperechoic or isoechoic groups (p less than 0.01 and p less than 0.05, respectively), and the incidence of hypothyroidism was significantly higher in the hypoechoic group than in the hyperechoic or isoechoic groups (p less than 0.001 and p less than 0.005, respectively). In addition, high titers of the antithyroid microsomal antibody (greater than or equal to 1280) were present more frequently in the hypoechoic group than in the hyperechoic or isoechoic groups (p less than 0.01 and p less than 0.05, respectively). There was no significant correlation between the cytomorphology and echogenicity of the thyroid in these cases. We conclude that sonography has two major uses in evaluating autoimmune thyroiditis: First, it is useful in excluding the coexistence of thyroid nodules; and second, marked hypoechogenicity of the thyroid implies an active cytotoxic autoimmune process and possibly a hypothyroid state.

Humans↗
PubMed1990

Margosa oil poisoning as a cause of toxic encephalopathy.

Margosa Oil is an extract of the seed of the Neem tree and is widely used as a traditional medicine by Indians in India, Sri Lanka, Burma, Thailand, Malaysia and Indonesia. Used mainly for external applications, it is often administered orally to neonates and infants regularly in small amounts. Margosa Oil causes toxic encephalopathy particularly in infants and young children. The usual features are vomiting, drowsiness, tachypnea and recurrent generalised seizures. Leucocytosis and metabolic acidosis are significant laboratory findings. Management is aimed primarily towards the control of convulsions although supportive management is equally important. Prognosis is usually good but fatalities and neurological deficits have been reported. We report here two infants with Margosa Oil poisoning presenting with encephalopathy.

Brain Diseases↗
PubMed1989

World-wide trends in multiple sclerosis mortality.

Mortality attributed to multiple sclerosis (MS) was analyzed for 35 countries around the world using World Health Organization reports from 1965 to 1984. Trends were plotted for the United States and Canada, for various regions of Europe, Israel, South America, Asia, Australia and some Pacific countries. In general, MS mortality has declined steadily in North America and most of western Europe as well as in countries with a western culture but has remained stable or increased in eastern and northern Europe. Although several Mediterranean countries reported a recent increased frequency of MS, it was not (yet?) evident in mortality data. Intensive prospective surveillance of MS frequency trends in selected regions of the world will determine the validity of the trends based on mortality.

Asia↗
PubMed1989

Stroke in the Lehigh Valley: racial/ethnic differences.

We investigated black/white differences in stroke rate (standardized morbidity), severity, and subtype, and the relative frequencies of 5 primary risk factors (hypertension, diabetes, myocardial infarction, other heart diseases, and transient ischemic attack [TIA]) using the Lehigh Valley Stroke Register. Blacks had a statistically significant higher, age-adjusted rate of stroke than whites. We found no differences in stroke severity using our measures but blacks had a statistically higher proportion of lacunar stroke, while whites had a higher proportion of embolic stroke. There were no differences in proportions of thrombotic stroke or intracerebral hemorrhage. The relative frequencies of hypertension, myocardial infarction, other heart diseases, and diabetes were higher for blacks, while the relative frequency of TIA was higher for whites. These observations are consistent with other reports that blacks have a higher frequency of stroke and tend to have more small-vessel cerebrovascular pathology than whites.

Age Factors↗
PubMed1987

Structure-activity relationships in an imidazole-based series of thromboxane synthase inhibitors.

Analogues of 4-[[2-(1H-imidazol-1-yl)-1-[[(4-methoxyphenyl)methoxy]methyl] ethoxy]methyl]benzoic acid (5m) were prepared and evaluated as thromboxane synthase inhibitors. A series of esters of 5m showed a parabolic relationship between lipophilicity and inhibition of TxB2 generation in intact platelets, with activities up to 50 times greater than that of dazoxiben. However, on administration to rabbits the ethyl ester 5d had a short duration of action, due to rapid metabolism and excretion via deesterification and beta-glucuronidation. Attempts at replacing the carboxylate group with other potential pharmacophores were unsuccessful.

Animals↗
PubMed1987

Thromboxane synthase inhibitors. Synthesis and pharmacological activity of (R)-, (S)-, and (+/-)-2,2-dimethyl-6-[2-(1H-imidazol-1-yl)-1-[[(4-methoxyphenyl)- methoxy]methyl]ethoxy]hexanoic acids.

A series of substituted omega-[2-(1H-imidazol-1-yl)ethoxy]alkanoic acid derivatives were synthesized and evaluated for their ability to inhibit thromboxane synthase both in vitro and in vivo. Compound 13 was identified as a potent and selective competitive inhibitor of human platelet thromboxane synthase having a Ki value of 9.6 X 10(-8) M. In collagen-treated human whole blood, 13 potentiated levels of 6-keto PGF1 alpha. Enantiospecific syntheses afforded the R and S enantiomers of 13, of which the S enantiomer 13b was the more potent. Compounds 13 and 13b were potent in vivo inhibitors of thromboxane synthase with good oral activity and duration of action.

6-Ketoprostaglandin F1 alpha↗
PubMedDate not supplied

Three-dimensional cytomorphology in fine needle aspiration biopsy of medullary thyroid carcinoma.

OBJECTIVE: To elucidate three-dimensional (3-D) cytomorphology in fine needle aspiration biopsy (FNAB) of medullary thyroid carcinoma (MTC). STUDY DESIGN: ENAB was performed on tumors from five patients with MTC. The aspirate was stained and observed under a light microscope (LM). The aspirate was also fixed, dehydrated, critical point dried, spattered with gold ions and observed with a scanning electron microscope (SEM). For transmission electron microscopy (TEM), the specimen was fixed, dehydrated, embedded in an Epon mixture, cut with an ultramicrotome, mounted on copper grids, electron doubly stained with uranium acetate and lead citrate, and observed with TEM. Findings under SEM were correlated with those under LM and TEM. RESULTS: Under SEM, 3-D cytomorphology of MTC displayed a disorganized cellular arrangement with indistinct cell borders in three cases. The cell surface was uneven and had granular protrusions that corresponded to secretory granules observed under TEM. In one case with multiple endocrine neoplasia type IIB, there were abundant granules on the cell surface. In one case of sporadic MTC with multinucleated tumor giant cells and small cells, granular protrusions also were noted on the cell surface. CONCLUSION: Granular protrusion was a characteristic finding in FNAB of MTC tinder SEM and might be helpful in the differential diagnosis.

Adult↗
PubMedDate not supplied

Three-dimensional cytomorphology and its relationship with clinical stage in fine needle aspiration biopsy of papillary thyroid carcinoma.

OBJECTIVE: To elucidate three-dimensional (3-D) cytomorphology and its relationship with clinical stage in fine needle aspiration biopsy (FNAB) of papillary thyroid carcinoma (PTC). STUDY DESIGN: FNAB was performed in tumors from 34 patients with PTC. The aspirate was stained and observed under a light microscope (LM). The aspirate was also fixed, dehydrated, critical point dried, spattered with gold ions and observed with a scanning electron microscope (SEM). Findings under SEM were correlated with the presentation under LM and also with clinical stage. As a control, FNAB was also performed on a normal part of the thyroid in six patients. RESULTS: Under SEM, normal thyroid cells appeared as round, scattered cells or sheets with a uniform honeycomb cellular arrangement. In PTC, cell sheets with uniform nuclear morphology under LM usually showed a uniform cell arrangement and with distinct cell borders under SEM. Cell sheets with nuclear pleomorphism under LM usually showed a more-disorganized arrangement and with indistinct cell borders under SEM. PTC at advanced clinical stages usually presented with a disorganized cell arrangement, indistinct cell borders and loss of microvilli. CONCLUSION: 3-D cytomorphology in FNAB of PTC was related to clinical stage and might be a prognostic factor for PTC.

Adult↗
PubMedDate not supplied

Stroke in the Lehigh Valley: seasonal variation in incidence rates.

We investigated the seasonal pattern of stroke using the Lehigh Valley Stroke Register. This register includes all patients hospitalized with stroke or transient ischemic attack (TIA) from among the 600,000 Lehigh Valley residents. Meterological data were obtained from the National Oceanic and Atmospheric Administration. The study, which uses 18 months of data, included 1,944 cases. Using single harmonic regression analysis, the seasonal pattern of TIA and infarction, but not hemorrhage, fit a sine-cosine wavefunction with a 12-month period (R2 = 41% and 36%, respectively). For infarction, the strongest seasonal pattern was exhibited for women of all ages and for both sexes in the age groups 65-74 and 75-84, but only the sine component was significant. The peak months for TIA were June-August, while the peak months for infarcts were February-April. Correlations between ambient temperature and each type of stroke were computed. A significant positive correlation for TIA was found (r = 0.57, p = 0.01). After adjusting for a 2-month lag between the low for infarction and the peak for temperature, a significant negative correlation was found (r = -0.64, p = 0.01). No significant correlation was found for hemorrhage. Possible reasons for the opposite relations of TIA and infarct are discussed.

Age Factors↗
PubMedDate not supplied

Acute stroke, hematocrit, and blood pressure.

A population-based study of the relation between hematocrit and stroke subtype was carried out among 2,077 individuals using the Lehigh Valley Stroke Register. This register identifies all stroke patients admitted to the 8 acute care hospitals serving the Lehigh Valley area of eastern Pennsylvania-western New Jersey. The mean hematocrit was higher in patients with lacunes than with thrombotic or embolic strokes (p = 0.02). However, when blood pressure was also considered the increase in hematocrit in patients with lacunar stroke was significant only when systolic hypertension (greater than or equal to 150 mm Hg) was also present (p = 0.029); no significant difference in hematocrit was found between stroke subtypes in normotensive individuals. Therefore, we cannot exclude the possibility that hypertension interacts with hematocrit in accounting for the observed association with lacunar infarcts. There was no trend for increased in-hospital mortality for stroke patients in either the low (less than or equal to 30, 30-36%) or high (greater than or equal to 47%) hematocrit groups.

Acute Disease↗
PubMedDate not supplied

Use of antihypertensive and antithrombotic medications after stroke in community-based care.

BACKGROUND: Secondary stroke prevention strategies include pharmacologic approaches to control hypertension and reduce thromboembolic risk. OBJECTIVE: To describe antithrombotic and antihypertensive medication use, and rates of blood pressure control in the Kansas City Stroke Study, a prospective stroke cohort receiving community-based care after primarily mild and moderate stroke. METHODS: Participants from 12 area hospitals provided information about medication use prior to stroke. Study personnel measured blood pressures at enrollment and at one, three, and six months, and collected medication data at six months during in-home assessment. RESULTS: Complete data at six months were available for 355 subjects with ischemic stroke, among whom 13% had atrial fibrillation and 67% had prior hypertension. Prior to stroke, only 45% of the patients were receiving any antithrombotic (anticoagulant and/or antiplatelet) therapy; this figure rose to 77% at six months. Antithrombotic treatment rates among those with atrial fibrillation were 59% before stroke and 83% at six months, including warfarin in 64%. Approximately 70% of subjects had controlled blood pressures one, three, and six months after stroke, defined as systolic blood pressure < or = 140 mm Hg and diastolic blood pressure < or = 90 mm Hg. Use of multiple antihypertensive agents was common; calcium-channel blockers and angiotensin-converting enzyme inhibitors were used most frequently. However, 19% of subjects with uncontrolled blood pressure were untreated at six months. CONCLUSIONS: Although room for improvement remains, these data suggest improved rates of antithrombotic and antihypertensive medication use after stroke in community-based care in a midwestern metropolitan community, compared with previous reports.

Aged↗