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Biomedical subjects

S M Zhou

Publications and source records attributed to S M Zhou.

At least 37 records · Page 2Linked to original sources
PubMed1994

A robust method of multileaf collimator (MLC) leaf-configuration verification.

Presents a novel and robust method for leaf-position verification with a multileaf collimator (MLC). On the portal image associated with an MLC-generated treatment field, all true treatment-held-edge lines are either parallel or perpendicular to each other. This unique feature of an MLC treatment field has been fully exploited by the authors' method. Employing a Hough-type transformation as an edge-line-orientation detector and a chamfer-matching method, the authors can find the best matching parameters (including translation, rotation and scaling) adaptively between a prescribed MLC leaf configuration and the actual treatment-held edges generated by the MLC system. This works even if the portal image is partially corrupted by noise or covered by compact bony structures. Comparing these parameters with clinically accepted tolerances, the authors can make a "go-or-no-go" decision quickly.

Algorithms↗
PubMed1994

[Analysis of 28 clinical cases and bone in stress around every tooth with pericementitis caused by occlusal trauma]

28 cases of pericementitis on occlusal trauma were observed,treated and followed up for 2 years;The bone in stress around every involved tooth was analysed according to the stress analysis by three demensinal photoelastic models loading excessive occlusal forces in various direction and coincided with the area of abnormality on the tooth radiograph.The result showed that the present methods of examination and treatment for tooth with traumatic pericementitis could diagnose exactly and cure effectively this disease;the rate of cure for 2 years was 86.7%,subtle occlusal adjustment by 3-4 appointments could maintain stable curative effect.It is suggested that clinicians should pay more attention to discover and treat both with traumatic pericementitis,the earliest clinical manifestation of both injury in occlusal trauma in order to protect them from severe injury in occlusal disharmony as well as periodontal trauma.

Journal Article↗
PubMed1994

[Influence of anterior occlusal contacts of complete dentures on mastication].

The photocclusion and mastication analysis of the complete dentures with or without the anterior occlusal contacts were made. The results indicated that there was no obvious differences among the maximum occlusal contact intensities of each tooth position in central occlusion. Under the functional condition the activity of the anterior temporal muscles was influenced and the mastication efficiency was decreased by the relatively stronger anterior occlusal contacts.

Aged↗
PubMed1994

Selenium supplement in the prevention of pregnancy induced hypertension.

The effect of selenium (Se) supplement on pregnancy was studied in 52 pregnant women with high risk factors of pregnancy induced hypertension (PIH). They were given natural Se dietetic liquid (100 micrograms/d) for 6-8 weeks during late pregnancy, and 48 controls were given placebo. They received similar routine prenatal care. The results revealed that Se supplement on the pregnant women prevented and decreased the incidence of PIH and gestational edema, and elevated the mother's blood Se level by 0.1008 +/- 0.091 ppm in the treated group while decreased by 0.0402 +/- 0.046 ppm in the control group (P < 0.01). The umbilical blood Se level was 0.2756 +/- 0.100 ppm in the treated group and 0.1544 +/- 0.051 ppm in the control (P < 0.01). The differences of the neonatal birth weight and the amount of postpartum hemorrhage between the two groups were not significant.

Adult↗
PubMed1994

[Amniotic fluid C-peptide in pregnancy with diabetes].

A prospective study on amniotic fluid C-peptide (AFCP) was made in 29 women with diabetic pregnancy and 23 non-diabetic control subjects. The mean concentrations of AFCP were found to be significantly higher in diabetic pregnancy than in non-diabetic pregnancy (P < 0.01) (diabetic group AFCP 1.89 +/- 1.53ng/ml; control group 0.88 +/- 0.51ng/ml). AFCP levels were related to the degree of blood glucose control during pregnancy and not to diabetic classification. The results show that fetal hyperinsulinemia reduced in these women that the achieved metabolic control of maternal blood glucose levels approached normal values. A higher neonatal complications occurred while AFCP was over 1.68ng/ml.

Amniotic Fluid↗
PubMed1993

[Effect of selenium supplement on prevention of pregnancy-induced hypertension].

We studied the effect of selenium supplement on 52 pregnant women with high risk factors of pregnancy-induced hypertension (PIH) who were given the natural Se dietetic liquid (100 micrograms/day) for 6-8 weeks during late pregnancy and 48 controls. They were subjected to the same prenatal care. Se supplement on the pregnant women prevented or lowered the incidence of PIH and gestational edema. Se supplement on the pregnant women elevated the mother's blood Se level (0.1008 +/- 0.091 ppm in the treated group vs 0.0402 +/- 0.046 ppm in the control group, P < 0.01) and umbilical blood Se level (0.2756 +/- 0.1 ppm in the treated group vs 0.1544 +/- 0.051 ppm in the controls, P < 0.01). The difference of the neonatal birth weight and the amount of postpartum hemorrhage between the two groups were not significant.

Adult↗
PubMed1993

[Effect of hypoxia on the conversion of angiotensin I to A II in pulmonary vascular endothelial cells].

The effect of hypoxia on intrapulmonary conversion of angiotensin I (A I) to angiotensin II (A II) was examined by using an isolated rat lung preparation perfused at constant flow and cultured calf pulmonary artery endothelial cells. The conversion rate of A I in endothelial cells of pulmonary vascular bed was found to be decreased in both acute hypoxic and chronic hypoxic (CH-5000, CH-8000) rats. The conversion rate of A I to A II was significantly higher in acute hypoxic rat lungs than that in denuded endothelial cells rat lungs. There was no significant difference between chronic hypoxic and denuded endothelial cells rat lungs. In cultured calf pulmonary artery endothelial cells (PAEC) exposed to hypoxia (3% O2) for 30 minutes the conversion of A I to A II was significantly reduced. In the time course of hypoxic exposure the conversion of A I to A II in cultured calf PAEC showed significant difference between hypoxia and normoxia. The results indicated that (1) Acute and chronic hypoxia impaired pulmonary conversion of A I to A II. (2) Effect of hypoxia on the pulmonary conversion of A I to A II is associated with the degree and the time of hypoxia.

Angiotensin I↗
PubMed1993

[Clinical analysis of perinatal outcome in gestational diabetes].

This retrospective study was carried out on 78 women with gestational diabetes during Nov. 1982-Oct. 1991. The study indicates that treatment of gestational diabetes can reduce the occurrence of macrosomia. Macrosomia occurred in 19.35% of the insulin-treated group, 21.05% of the diet-treated group, and 50% of the untreated group. Neonatal morbidity was decreased in good diabetic control group. A routine prenatal "50g glucose screen" in pregnant women with high-risk factor should be carried out in order to make early diagnosis of gestational diabetes. Delivery time should be choosen during 38-40 weeks of gestation.

Adult↗
PubMed1990

[Correlation of placental inflammatory changes in clinical infection in premature rupture of membranes].

Maternal and neonatal white blood cell counts, neonatal pharyngeal culture, and histologic examination of placenta were done in 55 term pregnancies with premature rupture of fetal membranes (PROM) and in 52 term pregnancies without PROM to study the correlation between placental inflammation and clinical outcome. The results were as follows: (1) A higher rate of chorionitis and chorionic plate inflammation exist in patients with PROM. The inflammation rate of chorionic plate was 90% in patients with labor lasting longer than 12 hours, and only 38% in patients with a duration less than 12 hours. The difference was highly significant (P less than 0.01). (2) The positive rate of neonatal pharyngeal culture was higher in the PROM group than that in the control group (P less than 0.01). (3) Inflammation of chorionic plate was seen in 6/6 of the cases with neonatal infection. The corresponding rate was only 38% in cases without neonatal infection (P less than 0.01). It is suggested that in patients with PROM, efforts should be made to shorten the time of labor and the neonates should be watched for possible infections in the presence of inflammation of the placenta, particularly the chorionic plate.

Bacterial Infections↗
PubMed1989

[Stress analysis of the periodontal ligament of the human tooth using a three-dimensional finite element method].

Three-dimensional finite element analysis is used to determine the physiological stress values in periodontal ligament (PDL). In comparison with the elastic modulus E of PDL, the E of dentin and bone are much larger. For the estimation of the stresses in PDL, the tooth and the supporting bone can be considered to be rigid. The finite element model of PDL of the mandibular right first molar consists of 210 elements (20-node isoparametric element) and 1612 nodes. Eleven load cases were selected in the study, which included the longitudinal occlusive load, buccal lingual lateral load, mesial-distal lateral load and other load cases to simulate the actual occlusive loads. The results obtained from this study lead to the following conclusions: 1. The loads which go through the physiological center of the tooth, the stresses induced by the loads which are compressive and relatively small. There are no tensile stresses. 2. Among eleven load cases studied in this work, the following three load cases are most harmful. a. The maximum tensile stress was found under mesial-distal lateral load; b. The maximum compressive stress was found under longitudinal occlusive load on the buccal groove or lingual groove; c. The highest stress concentration was found under buccal-lingual lateral load. The clinical significance of the results has also been discussed in the paper.

Biomechanical Phenomena↗
PubMed1988

Histologic chorioamnionitis in pregnancies of various gestational ages. II: Implications in preterm labor.

A retrospective review of placental materials (membranes, chorionic plate, umbilical cord) derived from preterm birth is reported. All those studied had intact membranes on admission and did not have spontaneous rupture. Those with preterm labor unresponsive to tocolysis, including those with brief and more prolonged labors, were compared with those delivered preterm because of maternal or fetal indications without labor. Those with labor had inflammatory changes in all three sites of greater frequency than those without labor. Those with longer labors had significantly higher rates of inflammation than those without labor. In this population, removing the influence of spontaneous rupture and labor over 6 hours long greatly diminished the likelihood of inferring that inflammation of the choriamniotic environment is a cause of preterm labor unresponsive to tocolysis.

Chorioamnionitis↗
PubMed1987

Histologic chorioamnionitis in pregnancies of various gestational ages: implications in preterm rupture of membranes.

A retrospective review of placental material derived primarily from preterm deliveries was conducted and inflammatory changes graded on a scale of 0-3. Reviewers were blind as to the clinical outcomes. Other reviewers, unaware of the pathologic results, surveyed the clinical data, and results were combined for analysis. The findings suggest that placental and membrane inflammation probably precedes preterm spontaneous rupture of membranes in 8-30% of cases without labor. The duration of ruptured membranes and labor enhance the frequency of inflammation. Inflammation is not associated with significant puerperal infection unless cesarean delivery occurs. Perinatal morbidity and mortality were not significantly enhanced nor associated with conservative management of spontaneous preterm rupture of membranes in this population beyond the influence of fetal weight and gestational age.

Birth Weight↗