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Biomedical subjects

S F Wang

Publications and source records attributed to S F Wang.

At least 55 records · Page 3Linked to original sources
PubMed1997

Measuring tibial cortical bone status by ultrasonic velocity.

BACKGROUND: Post-menopausal osteoporosis has become a serious public health problem with the increase of the geriatric population. Dual energy x-ray absorptiometry (DEXA) is the most common method for diagnosis of osteoporosis by quantitative change of bone, but recently there is increasing interest in measuring both qualitative and quantitative changes of bone by ultrasound. This study measured ultrasound velocity of anterior tibial cortex to evaluate the feasibility of detecting cortical bone status by speed of sound (SOS). METHODS: SOS in anterior tibial cortex was measured on 205 females referred from clinicians for routine bone mineral density (BMD) measurement. These females were divided into 2 groups. Group 1 consisted of 170 females aged from 30 to 75 years (mean: 55.2 +/- 9.3 years), who never received estrogen therapy. Group 2 consisted of 35 females in the post-menopausal status aged ranged from 45 to 69 years (mean: 51.5 +/- 3.5 years), who had received estrogen gel or oral estrogen tablet (0.625 mg/day) replacement therapy for prevention of postmenopausal osteoporosis for a period of 6 to 68 months (mean: 25.3 +/- 2.3 months). For precision test, 3 volunteers whose SOS was measured by 2 different operators were also enrolled in our study. BMD by DEXA of L-spine and/or hip was also performed on the same day of SOS examination. We analyzed the precision of this new method, calculated mean value of SOS to see if there was any difference with respect to pre- at, and post-menopausal status between estrogen users and nonusers by SOS, and tried to find the relationship of SOS with body habitus and BMD. RESULTS: Mean value of SOS of group 1 females was 3852 +/- 150.3 m/s, with peak value in the fourth decade. There were inverse correlation of SOS with age (r = -0.36, p < 0.0005) and the period after menopause (r = -0.32, p < 0.0005). The decreasing rate of SOS per decade from 31 to 50 years of age was 1.7%, while that of 51 to 70 years was 4.3% in group 1 females. With regard to menopausal status, there was significant difference of SOS between pre- and post-menopausal females (p = 0.01, ANOVA test), between at and post-menopausal females (p = 0.02). Significant difference (p < 0.05, ANOVA test) between group 2 estrogen users and group 1 postmenopausal nonusers was also noted. There was no evidence of correlation of body weight or height with SOS. Both inter- and intra-operator precision of SOS was under or equal to 0.32%. Moderately correlation between SOS and BMD was noted. CONCLUSIONS: Our study demonstrated good precision in SOS measurement of tibial cortical status. It was inversely correlated with age and post-menopausal period; it also significantly discriminated estrogen users from nonusers, and pre-, at from post-menopausal subgroups. However, for further evaluation of the relationship between SOS and the most severe complication of osteoporosis, i.e. osteoporotic fracture, population-based long-term followup is still required.

Adult↗
PubMed1997

[Epidemiological features and determinants of road injury in China].

Information on road injury with analyses on the epidemiological features and determinants of fatality rate with prevention and control of road injury was presented in this paper. From 1951 to 1994, road injury and motor vehicle deaths had a continuous increase by 43 and 78 times respectively. Since 1987 about 250,000 cases, 5000 deaths and 15,000 trauma cases caused by road crashes year after year. The fatality rate increased by an average of 12.9% increase per year from 1984 to 1994 (from 2.43 to 5.56 per 100,000 pop). Zhejiang, Guangdong, Liaoning, Sichuan and Jiangsu occupied the first five places in 30 provinces, accounted for over 45% of total road injuries and one thirds of road fatalities. Both incidence and death rate were lowest in Beijing City and highest in Zhejiang Province. Three-quarters of the fatality on road injury were occurred on smooth and straight pavement in sunny days. Over 60% of the motor vehicle deaths were young males (age 20-50 yrs). Classified by occupation, majority of the victims were peasants (55%) and workers (19%). Two thirds of the road fatalities were pedestrians, bicycle riders and passengers. Human factors including driver's irresponsibility, non-licensing, bicycle rider and pedestrian carelessness, etc. were notified that accounted for over 90% of the causes for road injury. Primary causes from the drivers were rules and regulations violation, absent-mindedness, driving after drinking alcohol. The risk factors of road injuries were the increase of motor vehicles and traffic congestion. It is also necessary to improve the traffic safety knowledge among residents.

Accidents, Traffic↗
PubMed1997

Lysis of pig endothelium by IL-2 activated human natural killer cells is inhibited by swine and human major histocompatibility complex (MHC) class I gene products.

We have previously described a form of xenograft rejection, mediated by natural killer (NK) cells, occurring in pig-to-primate organ transplants beyond the period of antibody-mediated hyperacute rejection. In this study, two distinct NK activation pathways were identified as mechanisms of pig aortic endotheliual cell (PAEC) lysis by human NK cells. Using an antibody-dependent cellular cytotoxicity (ADCC) assay, a progressive increase in human NK lysis of PAEC was observed following incubation with human IgG at increasing serum titer. In the absence of IgG, a second mechanism of PAEC lysis by human NK cells was observed following activation with IL-2. IL-2 activation of human NK cells increased lysis of PAEC by over 3-fold compared with ADCC. These results indicate that IL-2 activation of human NK cells induces significantly higher levels of lytic activity than does conventional ADCC involving IgG and FcRIII. We next investigated the role of MHC class I molecules in the regulation of NK lysis following IL-2 activation. PAEC expression of SLA class I molecules was increased by up to 75% by treatment with human TNFa. Following treatment with TNFa at 1 u/ml, IL-2 activated human NK lysis of PAEC was inhibited at every effector:target (E:T) ratio tested. Maximal effect occurred at an E:T ratio of 10:1, with TNFa inhibiting specific lysis by 59% (p < 0.01). Incubation with an anti-SLA class I Mab, but not IgG isotype control, abrogated the protective effects of TNFa on NK lysis of PAEC, suggesting direct inhibitory effects of SLA class I molecules on human NK function. To investigate whether human MHC class I molecules might have similar effects on human NK lysis of PAEC, further experiments were performed using a soluble peptide derived from the alpha-helical region of HLA-B7. Incubation with the HLA-B7 derived peptide significantly reduced the IL-2 activated NK lytic activity against PAEC in a dose-dependent fashion. Maximal effect occurred at a concentration of 10 mg/ml, where an 8-fold reduction in IL-2 augmented NK lysis was observed (p < 0.01). These results suggest that IL-2 activated human NK lysis of porcine xenografts may be inhibited by strategies which increase PAEC expression of SLA class I molecules, introduce HLA class I genes into PAEC, or use soluble HLA class I peptides.

Animals↗
PubMed1996

Circulating human mononuclear cells exhibit augmented lysis of pig endothelium after activation with interleukin 2.

In immunohistochemical studies investigating the cellular infiltrates in pig xenografts undergoing delayed rejection by newborn and adult primate recipients, we observed extensive infiltration with primate macrophages and natural killer (NK) cells. To extend these studies in vitro, we investigated the functional properties of human NK cell precursors with respect to their potential interactions with pig aortic endothelial cells (PAEC). Using a short-term 51Cr release assay, human peripheral blood mononuclear cells (PBMC) demonstrated spontaneous and interleukin (IL) 2 augmented lytic activity against PAEC which increased with increasing effector to target cell ratio. Treatment of human PBMC with anti-CD2 significantly reduced this NK lytic activity by IL-2-activated PBMC. Finally, we investigated the effects of PAEC treatment with certain macrophage-derived human cytokines on adhesion of IL-2-activated human PBMC. Treatment of PAEC with IL-1 and tumor necrosis factor-alpha, in a dose-dependent manner, increased adherence of IL-2-activated human PBMC. These results demonstrate that humans contain circulating NK cells capable of lysing PAEC after activation with IL-2, that the mechanism involves interactions between CD2 and its ligand on porcine endothelium, and that these interactions may be influenced by macrophage-derived cytokines produced at the site of xenograft rejection.

Animals↗
PubMed1996

Immunohistochemical localization of neurotransmitters utilized by neurons in the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) that project to the oculomotor and trochlear nuclei in the cat.

The rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) contains excitatory and inhibitory burst neurons that are related to the control of vertical and torsional eye movements. In the present study, light microscopic examination of the immunohistochemical localization of amino acid neurotransmitters demonstrated that the riMLF in the cat contains overlapping populations of neurons that are immunoreactive to the putative inhibitory neurotransmitter gamma-aminobutyric acid (GABA) and the excitatory neurotransmitters glutamate and aspartate. By using a double-labelling paradigm, GABA-, glutamate-, and aspartate-immunoreactive neurons in the riMLF were retrogradely labelled by transport of horseradish peroxidase (HRP) from the oculomotor and trochlear nuclei. Electron microscopy showed that the oculomotor and trochlear nuclei contain synaptic endings that are immunoreactive to GABA, glutamate, or aspartate. Each neurotransmitter-specific population of synaptic endings has distinctive ultrastructural and synaptic features. Synaptic endings in the oculomotor and trochlear nuclei that are anterogradely labelled by transport of biocytin from the riMLF are immunoreactive to GABA, glutamate, or aspartate. Taken together, the findings from these complimentary retrograde and anterograde double-labelling studies provide rather conclusive evidence that GABA is the inhibitory neurotransmitter, and glutamate and aspartate are the excitatory neurotransmitters, utilized by premotor neurons in the riMLF that are related to the control of vertical saccadic eye movements.

Animals↗
PubMed1996

Morphology and soma-dendritic distribution of synaptic endings from the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) on motoneurons in the oculomotor and trochlear nuclei in the cat.

The morphology and soma-dendritic distribution of anterograde biocytin-labelled rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) synaptic endings in the oculomotor and trochlear nuclei have been examined by electron microscopy by using both preembedding immunoperoxidase and postembedding immunogold methods. The results indicate that three morphological types of riMLF synaptic endings are distinguishable on the basis of synaptic vesicle morphology (spheroidal, pleiomorphic, or ellipsoidal) and postsynaptic membrane specializations (asymmetrical or symmetrical). All three morphological types of riMLF synaptic endings establish synaptic connections predominantly with dendrites. Synaptic endings that contain ellipsoidal synaptic vesicles have a more proximal soma-dendritic distribution than those that contain either spheroidal or pleiomorphic synaptic vesicles. Furthermore, all three morphological types of synaptic endings are encountered in the same motoneuron subdivisions of the oculomotor and trochlear nuclei in the same experiments. The findings suggest that subregions of the riMLF contain coexistent populations of excitatory and inhibitory premotor neurons that are related to opposite directions of vertical saccadic eye movements but that project to the same motoneuron subgroups on the ipsilateral side. Both the morphology and the mode, pattern, and soma-dendritic distribution of saccade-related riMLF synaptic endings that establish synaptic connections with vertical motoneurons differ from those of excitatory and inhibitory second-order vertical vestibular synaptic endings. These differences in the synaptic organization of riMLF and second-order vestibular inputs to oculomotor and trochlear motoneurons may be related to differences in the information transferred by each source, the riMLF input conveying eye-velocity signals, and the vestibular input conveying eye-position signals.

Animals↗
PubMed1996

Spatial organization of premotor neurons related to vertical upward and downward saccadic eye movements in the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) in the cat.

The rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) contains premotor neurons that are related to the control of vertical and torsional saccadic eye movements. In the present study, complimentary light microscopic anterograde biocytin and retrograde horseradish peroxidase experiments have been performed to determine the organization of premotor neurons in the riMLF in the cat that are related intimately to the vertical motoneuron populations in the oculomotor and trochlear nuclei. The results indicate a rostral-caudal topographic arrangement of neurons in the riMLF that is related to the target projections to vertical downward (inferior rectus and superior oblique) and vertical upward (superior rectus and inferior oblique) motoneurons, respectively, in the oculomotor and trochlear nuclei. Both the anterograde and the retrograde studies are consistent, in that they demonstrate the tendency for downward and upward riMLF neurons to be separated spatially by a distance of approximately 0.5 mm in the rostral-caudal axis of the nucleus. The riMLF projections to inferior oblique and superior oblique motoneurons are predominantly ipsilateral. Projections to inferior rectus and superior rectus motoneurons, however, are bilateral, and, presumably, they provide one means for assuring the conjugacy of vertical saccadic eye movements. Because premotor burst neurons that encode parameters for upward or downward saccades are intermingled within the riMLF, and excitatory and inhibitory premotor neurons also coexist in this region, the findings from this study suggest that subregions of the riMLF contain coexistent populations of excitatory and inhibitory neurons that are related to opposite directions of vertical eye movements. The spatial segregation of excitatory premotor neurons in the riMLF that are related to vertical upward vs. downward movements, furthermore, provides a basis for the interpretation of vertical upward and/or downward gaze palsies that might result from discrete lesions at the mesodiencephalic junction in humans.

Animals↗
PubMed1995

Intra - and inter-examiner reproducibility in constant force probing.

This study evaluated intra- and inter-examiner reproducibility for a conventional manual probe versus a computer-interfaced force-controlled periodontal probe. 2 examiners recorded probing depths (PD) and relative attachment levels (AL) at 1128 sites in 15 periodontal maintenance patients. Each site was evaluated 2x, 7 to 10 days apart by both examiners. Probing force for the electronic probe was 15 g. PD intra-examiner reproducibility (within +/- 1.0 mm) for shallow sites (PD < or = 3 mm) was 98.6% versus 91.5% for the conventional versus the electronic probe for examiner 1 and 98.5% versus 88.7% for examiner 2. Corresponding values for deeper sites (PD > 3 mm) were 96.4% versus 85.9% for examiner 1 and 95.1% versus 77.0% for examiner 2. Generally, AL intra-examiner reproducibility was 1 to 3% lower than for PD. PD inter-examiner reproducibility (within +/- 1.0 mm) was 99.2% versus 90.7% for the conventional versus the electronic probe, respectively, for shallow sites and 95.4% versus 76.9% for deeper sites. AL inter-examiner reproducibility (within +/- 1.0 mm) was 1 to 5% lower than for PD. Both intra- and inter-examiner reproducibility was higher for anterior than for posterior sites. Mean PD and AL were similar for both examiners. However, the electronic probe consistently recorded 0.1 to 0.2 mm higher values than the conventional probe. Standard deviations indicated a greater variability for electronic than for manual probing. The results suggest that intra- and inter-examiner reproducibility may not necessarily be higher with an electronic, force-controlled periodontal probe than with a conventional manual probe.

Adult↗
PubMed1995

Reproducibility of periodontal probing using a conventional manual and an automated force-controlled electronic probe.

A total of 1,128 sites in 15 periodontal maintenance patients were examined twice, 7 to 10 days apart, to evaluate reproducibility of periodontal probing by a conventional manual and an automated force-controlled electronic probe. Probing depths (PD) and relative attachment levels (AL) were recorded to the nearest 0.5 mm with both instruments. At each visit, all sites were probed first with the conventional and then with the electronic probe. Reproducibility of PD at shallow sites (PD < or = 3 mm) by the manual probe was 59.1% for exact agreement and 98.6% within +/- 1.0 mm variation. For the electronic probe, corresponding values were 41.3% and 91.5%, respectively. Reproducibility of PD measurements at deeper sites (PD > 3 mm), was 33.0% for exact match and 96.4% within +/- 1.0 mm for the manual and, correspondingly, 31.7% and 85.9% for the electronic probe. Reproducibility of AL followed a similar pattern, but was consistently lower than for PD. Reproducibility was consistently higher for anterior than for posterior sites and, for some comparisons, higher in the maxilla than in the mandible. These differences were smaller for the manual than for the electronic probe. Time required to complete the probing was longer for the conventional probe than for the electronic instrument. Under the prevailing study conditions, the automated force-controlled electronic probe failed to offer significant advantages over the conventional manual probe.

Adult↗
PubMed1993

Obstructive intestinal herniation due to improper use of a seat belt: a case report.

The term "seat belt syndrome" has been used to describe injuries to the abdominal viscera caused by seat belts during car accidents. These injuries are usually sustained as a result of the rapid deceleration that occurs in front-end collisions, with the consequent compression of the abdominal viscera. The spectrum of injuries includes intestinal perforation or stenosis, mesenteric disruption, and lumbar fracture-dislocation. We present an uncommon case of obstructive herniation in a 2-year-old girl which we believe was due to improper use of a seat belt.

Child, Preschool↗
PubMed1993

Bone mineral content of two populations of Chinese children with different calcium intakes.

Bone mineral content (BMC) of 5-year-old Chinese children (115 children in Jiangmen, China and 128 children in Hong Kong) was evaluated by single-photon absorptiometry at the distal 1/3 radius. The mean (S.D.) calcium intakes of children of Jiangmen and Hong Kong were 244 (46) and 542 (332) mg/day, respectively. The mean BMC, weight and height of Jiangmen children were significantly less than Hong Kong children by 14%, 10% and 4%, respectively (P < 0.001). Multiple regression analysis showed that 62% of the variance in BMC was explained by bone width (BW), weight and regional location (P < 0.0001). A regional difference in BMC of 0.0303 g/cm (P < 0.0001) still remained after adjusting for BW and weight by multiple regression analysis. When comparing sub-groups of children in the two regions with comparable low current calcium intake at 5 years, the BMC of Jiangmen children was still significantly lower than Hong Kong children even when potential confounders were adjusted (P < 0.003). The study suggests that the regional discrepancy in BMC might be explained by long-term habitual calcium intake and physical activity.

Absorptiometry, Photon↗
PubMed1992

Aspergillosis of the paranasal sinuses.

The CT appearances of 13 cases of pathologically proven aspergillosis involving paranasal sinuses were reviewed. Symptoms included rhinorrhea, nasal obstruction, headache, facial pain and foul smell from the nose. At operation, these lesions appeared yellowish, brownish, grey or black in colour, and contained dirty or muddy material. Microscopic examination of the tissue removed showed an Aspergillus ball with chronic inflammation but without invasion of the nasal or sinus mucosa in 6 cases, and tissue invasion with necrosis and inflammation in 7. The structures involved, in order of frequency, were: maxillary sinus, nasal cavity, ethmoid sinus, orbit and cavernous sinus. The orbit was involved in 2 cases, therefore categorized as invasive; the other 11 cases were non-invasive as judged by CT. Calcification was seen in the lesions of 9 cases. In most cases the adjacent bony structures showed areas of erosion and sclerosis. Aspergillosis should be suspected in the presence of a mass in the paranasal sinuses or nasal cavity with calcification within it, which may not appear solid or dense and is separate from the walls of the sinus.

Aged↗
PubMed1990

The variability of 24-hour, overnight 12-hour, and morning one-hour, urinary albumin excretion in normoalbuminuric and microalbuminuric hospitalized diabetics.

Albumin excretion rates (AER) of three consecutive days in different urine collection periods were measured in 7 hospitalized microalbuminuric diabetics (Ma DM) and 7 normoalbuminuric diabetics (Na DM). They were divided on the basis of an initial overnight urinary AER below or above 10 micrograms/min. The percentage of variation coefficients (% CV) of 24-hour, overnight 12-hour, and morning one-hour urine collections in Ma DM were 29.9%, 31.8% and 50.9%, respectively; while in Na DM group were 60.0%, 60.3% and 74.5%, respectively. There was no significant difference in the variation of AER among the three different urine collection procedures in both Ma DM and Na DM groups, or for similar urine collection between the two groups. The initial AER was compared to the subsequent two AERs in overnight 12-hour collection. The results were that three Ma DM patients had a subsequent AER below 10 micrograms/min and two Na DM patients had a subsequent AER above 10 micrograms/min on a single occasion. Therefore, the high variability of both groups would be expected to result in category changes. Multiple urine collections are needed to detect the early diabetic nephropathy for the hospitalized diabetics.

Aged↗
PubMed1987

[Detection of cytomegalovirus (CMV) DNA sequence in biopsy samples of cervical cancer].

Biopsy samples of the cervical cancer and cervicitis were analysed by HCMV-DNA hybridization method. The results indicated that HCMV-DNA was detected in 21 (36%) of 59 cervical cancer and 6 (21%) of 28 cervicitis specimens, using 32P-DNA probe containing transformation gene (14% of total genome) to hybridize. None of 25 cervical cancer and 19 cervicitis samples showed positive HCMV-DNA, using 32P-DNA probe without transformation gene (76% of total genome). The preliminary results show that the sequence of CMV transformation gene is present in about one third of cervical cancer and one fifth of cervicitis biopsy samples tested. This detection rate is lower than that of Taiwan Province and Africa, and slightly higher than that of the USA and Finland. The relation between the HCMV and cervical cancer is being further studied.

Base Sequence↗