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Biomedical subjects

H H Cheng

Publications and source records attributed to H H Cheng.

At least 91 records · Page 5Linked to original sources

Recent advances in the use of Doppler waveform indices in the antenatal assessment of intrauterine growth retardation.

Doppler ultrasound has been advocated as a useful tool to evaluate pregnancies with intrauterine growth retardation (IUGR). However, many previous studies have used smallness for gestational age (SGA) at birth to define IUGR. The ability of Doppler ultrasound to predict SGA, neonatal morphometric indices of wasting such as a low ponderal index, and perinatal morbidity is reviewed. Doppler assessment of the umbilical and uteroplacental vasculatures were inferior to ultrasound measurements of fetal size in the prediction of SGA. In low risk fetuses, umbilical artery waveform indices were of limited value in the prediction of neonatal morphometric indices of wasting. Within a group of high risk fetuses, Doppler assessment of the umbilical artery and, in particular, the middle cerebral and aortic vessels, were useful in predicting fetuses with neonatal wasting. Similar findings were noted in the prediction of perinatal morbidity. The review confirms the usefulness of umbilical artery Doppler waveform indices in the antenatal assessment of IUGR. Whilst preliminary studies appear to suggest that Doppler waveform indices of the middle cerebral and aortic vessels may confer an additional advantage in the antenatal assessment of IUGR, randomized controlled trials evaluating their effect on perinatal outcome and studies on the reproducibility of these indices need to be carried out before their widespread introduction into obstetric practice.

Cerebral Arteries↗

Genetic structure and symbiotic characteristics of a bradyrhizobium population recovered from a pasture soil.

We examined the genetic structure and symbiotic characteristics of Bradyrhizobium isolates recovered from four legume species (Lupinus albus [white lupine], Lupinus angustifolius [blue lupine], Ornithopus compressus [yellow serradella], and Macroptilium atropurpureum [sirato]) grown in an Oregon soil. We established that multilocus enzyme electrophoresis (MLEE) can provide insights into the genetic relatedness among Bradyrhizobium strains by showing a positive correlation (r = >/=0.90) between the relatedness of Bradyrhizobium japonicum strains determined by MLEE at 13 enzyme loci and that determined by other workers using either DNA-DNA hybridization or DNA sequence divergence estimates. MLEE identified 17 electrophoretic types (ETs) among 95 Bradyrhizobium isolates recovered from the four hosts. Although the overall genetic diversity among the ETs (H = 0.69) is one of the largest measured to date in a local population of any soilborne bacterial species, there was no evidence of multilocus structure (linkage disequilibrium) within the population. The majority of the isolates (73%) were represented by two closely related ETs (2 and 3) which dominated the root nodules of white lupine, serradella, and siratro. In contrast, ET1 dominated nodules of blue lupine. Although representative isolates from all of the 17 ETs nodulated siratro, white lupine, blue lupine, and big trefoil (Lotus pedunculatus), they were either completely ineffective or poorly effective at fixing nitrogen on these hosts. Despite the widespread use of serradella as a surrogate host for lupine-nodulating bradyrhizobia, 7 of the 17 ETs did not nodulate this host, and the remaining 10 ETs were ineffective at fixing nitrogen.

Journal Article↗

Microsatellite markers for genetic mapping in the chicken.

Microsatellite markers have been found to be abundant, evenly distributed, and highly polymorphic in a number of eukaryotic genomes. The objective of this study was to determine the utility of (TG)n microsatellites in the chicken. A chicken library enriched for (TG)n repeats was generated and 42 unique clones containing (TG)n microsatellites were identified and sequenced. The number of uninterrupted TG repeats ranged from 4 to 14 with an average of 7.8, which was considerably less than the number of repeats found in mammalian species. When primers designed to amplify across the (TG)n microsatellites were used in polymerase chain reactions (PCR) containing genomic chicken DNA, 19 of the 33 primer sets examined yielded polymorphisms in at least one of the three sets of chicken families: 15, 11, and 11 primer sets detected polymorphisms in the East Lansing (EL) reference population, the Compton (C) reference family, and between Line 63 and Line 72 chickens, respectively. The polymorphic microsatellite markers in the EL and C reference families were genetically mapped. Nine and seven mapped markers in the EL and C reference families, respectively, are polymorphic between Line 63 and Line 72, indicating that microsatellite markers will greatly enhance the ability to genotype specific loci of any chicken population.

Animals↗

The role of maternal serum alpha-fetoprotein, human chorionic gonadotrophin and oestriol in the antenatal screening of Down's syndrome.

The use of maternal age alone to identify pregnant mothers at risk of a fetus with Down's syndrome has recently been supplemented by maternal serum screening using biochemical markers such as alpha-protein, human chorionic gonadotrophin and oestriol. These tests have been reported to increase the sensitivity of antenatal detection of such fetuses from 35% to 67% with a false positive rate of 5%. However, these maternal serum markers may be affected by maternal weight, the smoking history of mothers and diabetes mellitus. Furthermore, such sensitivities are achieved only when gestational age is assessed accurately by ultrasound. Many further studies need to be carried out before the introduction of maternal serum screening into routine obstetric practice in Singapore. These include studies on the incidence of Down's syndrome in the local population, studies on the distribution of these serum markers in the second trimester of pregnancy, sensitivities and positive predictive values of such a test in the local population as well as the socio-economic implications of implementing such a screening test in the local obstetric population.

Adult↗

Birth defects--the state of awareness amongst mothers.

Birth defects have in recent years become the major cause of perinatal morbidity and mortality. The incidence of birth defects is between 2% to 6% of all live births. However, from a survey carried out in Singapore General Hospital (SGH), the majority of mothers enter pregnancy without realising the risks that they or their offspring may face. Only 20% to 25% of mothers were aware of the actual incidence of birth defects, and only 2.5%-10% knew that the risk of Down Syndrome (DS) increases with maternal age. However, the use of ultrasound is now well accepted and is considered a necessary investigation by 90% of the mothers surveyed.

Congenital Abnormalities↗

Serum and ascitic concentration of C3, C4 and protein in cirrhotic patients with spontaneous bacterial peritonitis.

BACKGROUND: Lower concentration of ascitic or serum complement (C3, C4) or protein has been reported to participate in the development of spontaneous bacterial peritonitis (SBP). In Taiwan, the etiology of hepatic cirrhosis is mainly post-hepatic and SBP is the common complication. This study aims to determine the role of protein and complements in the pathogenesis of SBP. METHODS: 119 cirrhotic patients were divided into two groups, 30 SBP and 89 non-SBP. The concentrations of ascitic and serum complement and protein were measured for comparison. RESULTS: The ascitic and serum C3, C4 and protein levels were significantly lower (P < 0.05) in patients with SBP than in non-SBP patients. No significant differences were noted in the ascites/serum ratio of C3, C4 and protein in patient with or without SBP. CONCLUSIONS: Low levels of ascitic and serum protein and complements, C3 and C4, may be prone to develop SBP in our patients mostly with post-hepatitic cirrhosis.

Aged↗

Birth defects--the state of awareness.

As doctors and nurses are the primary sources of medical information, a simple survey was conducted in 1992 among doctors and nurses to determine their level of awareness of the incidence of and risk of having an abnormal as well as their knowledge of the use of ultrasound in pregnancy. Only 10% of doctors and 23% of nurses were aware that the general risk of having an abnormal baby is greater than 1%. Only 37% and 17% of doctors and nurses respectively were aware that the best time to screen for structural abnormalities was indeed at approximately 20 weeks gestation.

Attitude of Health Personnel↗

Cohort study of HIV infection among drug users in Ruili, Longchuan and Luxi of Yunnan Province, China.

In March 1992, KAP investigation and HIV blood test were carried out for 860 drug users and 82 spouses in Ruili, Luxi, Longchuan of Yunnan Province, China. The results showed that there were 285 injecting drug users (IDUs) (33.1%) among 860 drug users. Among 282 blood samples of IDUs, the HIV infection rate was 49.0%, highest in Ruili (81.8%, 63/77), then Longchuan (44.6%, 74/166), lowest in Luxi county (5.1%, 2/39). Twelve new HIV(+) were found from 75 persons, who had been tested as HIV(-) in recent two years. Sixty-two blood samples were collected among 82 spouses of IDUs with HIV(+), and 6 were HIV(+) (9.8%), with an increase of 6.7% compared with results of the investigation two years ago (3.1%, 2/64).

China↗

Fetal urine biochemistry in the assessment of obstructive uropathy.

In 60 fetuses with obstructive uropathy, sodium, total calcium, urea, and creatinine were measured in samples obtained by "urodochocentesis" or pyelocentesis at 16 to 36 weeks' gestation. The patients were retrospectively assigned into two groups on the basis of outcome. Group 1 (n = 20) included infants who either had normal postnatal renal function or absence of prenatal renal dysplasia. Group 2 included infants who either had histologic evidence of renal dysplasia or subsequently developed renal failure. In group 1 the urinary sodium decreased and creatinine increased with gestation, demonstrating maturation in fetal renal function. In group 2 the urinary sodium and calcium were higher and the urinary urea and creatinine were lower than in group 1. The best predictor of outcome was the combination of either high calcium or high sodium with a positive predictive value of 91.3% and negative predictive value of 77.7%. In the antenatal evaluation of obstructive uropathy, fetal urinary biochemistry provides useful information for more accurate counseling of the parents and a rational basis for selecting patients who may benefit from intrauterine therapeutic interventions.

Creatinine↗

Fetal renal defects: associated malformations and chromosomal defects.

During a 6-year period (1985-1990) blood karyotyping was performed in 682 fetuses with renal defects. There were: 276 fetuses with mild hydronephrosis; 206 with moderate/severe hydronephrosis; 173 with multicystic dysplasia, and 27 with renal agenesis. The overall incidence of chromosomal abnormalities was 12% (trisomies, n = 63; deletions, n = 9; triploidies, n = 5, and sex chromosome aneuploidies, n = 8). There were more than twice as many males than females, but the incidence of chromosomal defects in females was almost double (18%) than in males (10%). Furthermore, compared to the overall maternal age-related risk, the risk for fetal chromosomal abnormalities was three times higher when there was an isolated renal defect and thirty times higher when there were additional malformations. The risk of chromosomal abnormalities was similar for fetuses with unilateral or bilateral involvement, different types of renal defects, urethral or ureteric obstruction, and oligohydramnios or normal/reduced amniotic fluid volume. Nevertheless, the patterns of chromosomal abnormalities, and consequently that of associated malformations, were related to the different types of renal defects.

Abnormalities, Multiple↗

Fetal gastro-intestinal and abdominal wall defects: associated malformations and chromosomal abnormalities.

During an 8-year period (1983-1991), blood karyotyping was performed in 235 fetuses with abdominal wall or gastro-intestinal tract defects. The overall incidence of chromosomal abnormalities was 29% (trisomy 21, n = 12; trisomy 18, n = 44; trisomy 13, n = 7; deletion of the short arm of chromosome 5, n = 1; unbalanced translocation involving chromosomes 4 and 15, n = 1; triploidy, n = 1; Klinefelter's syndrome, n = 1; and Beckwith-Wiedemann syndrome with mosaic duplication 11p15, n = 1). The karyotype was abnormal in 42 (36%) of the 116 fetuses with exomphalos, in none of the 26 with gastroschisis, in 10 (43%) of the 23 with duodenal atresia, in 18 (75%) of the 24 with lack of visible stomach, in 1 (4%) of the 24 with dilated bowel and in 2 (7%) of the 27 with echogenic hepatic nodules or abdominal cysts. Abnormal karyotypes were more commonly encountered when there was ultrasonographic evidence of multiple malformations (43%) compared to isolated defects (2%). Survival in fetuses with exomphalos (33%), absent stomach (4%), and large bowel obstruction (13%) was poor, whereas in those with gastroschisis (73%) or abdominal cysts (88%) survival was high; in small bowel obstruction and in duodenal atresia, survival was 65 and 57%, respectively.

Abdominal Muscles↗

Myositis ossificans progressiva mimicking ankylosing spondylitis: a case report.

Myositis ossificans progressiva is a rare disorder of young adults characterized by ossification of the connective tissue of the voluntary muscles and ligaments. Although it is trauma-related, up to 40-60% of these patients have no history of previous injury. A young female with marked kyphosis and ankylosis of the spine presented with a recent onset of a rapidly growing painful mass over the anterior aspect of her left shoulder. She received an excisional biopsy but recurrent ossification developed soon after. It then spread to the biceps muscle with subsequent contracture deformities of the shoulder and elbow joints. A plain radiogram of her spine revealed similar characteristics of ankylosing spondylitis. However, the final diagnosis was made by the pathognomonic ectopic ossification of muscles and para-articular soft tissue. Despite poor response of the established constracture, the painful mass did respond well to prednisolone treatment within 2 months, in terms of size and consistency.

Adult↗

Helicobacter pylori, gastritis and duodenitis in the healing process of duodenal ulcer.

The occurrence of antral gastritis, duodenitis, gastric metaplasia and Helicobacter pylori (H. pylori) were compared between 63 endoscopically proven duodenal ulcer (DU) patients and 34 non-ulcer dyspepsia (NUD) patients with no ulcer history and no ulcer present as documented by endoscopy. The DU group showed a significantly higher rate of active antral gastritis (89% vs 41% p less than 0.05), a higher antral H. pylori carrying rate (76% vs 27% p less than 0.01), a higher rate of active chronic duodenitis (75% vs 32% p less than 0.05), and a higher rate of gastric metaplasia in the duodenal bulb (68% vs 27% p less than 0.05) than the NUD group. The H. pylori carrying rate in the bulb was 16% in the DU group and 0% in the NUD group. The difference is evident, although it is statistically insignificant. All 10 cases carrying H. pylori in the duodenum in the DU group had active chronic duodenitis with gastric metaplasia. Further evaluation of the variables (rate of active antral gastritis and duodenitis and the carrying rate of H. pylori in the antrum and bulb) showed no difference between different ulcer stages (active, healing, or scarred). The above findings strongly suggest a close relation between H. pylori and duodenal ulcer. However, the low occurrence rate of the bacteria in the bulb can only indicate a partial etiologic role of the bacteria in DU. No improvement in antral gastritis, duodenitis and H. pylori occurrence, despite the healing of an ulcer, is in agreement with the naturally high recurrence rate of duodenal ulcers.

Duodenal Ulcer↗

Cleavage of the cII protein of phage lambda by purified HflA protease: control of the switch between lysis and lysogeny.

The activity of the cII protein of phage lambda is probably the critical controlling factor in the choice of the lytic or lysogenic pathway by an infecting virus. Previous work has established that cII activity is regulated through the turnover of cII protein; the products of the hflA and hflB loci of Escherichia coli are needed for a degradative reaction, and lambda cIII functions in stabilizing cII. By using the cloned hflA locus, we have purified a cII-cleaving enzyme that we term HflA. Purified HflA contains three polypeptides; at least two of the subunits are products of the hflA region, and the third is probably a cleavage product of the larger of these two hflA-encoded polypeptides. The HflA protease activity cleaves cII to small fragments. We conclude that the switch between lambda developmental pathways involves regulated cleavage of cII by the specific protease HflA.

Bacteriophage lambda↗

Free transplantation of venous network pattern skin flap.

We report a patient treated by transplantation of a venous network pattern skin flap containing two superficial cutaneous veins. Through one of the veins, arterial blood passed into the capillaries, restoring circulation and ensuring survival of the flap.

Adult↗

A class of Escherichia coli proteins controlled by the hflA locus.

The HflA protein of Escherichia coli is critical for the choice of the lytic or lysogenic pathway by bacteriophage lambda. To investigate whether HflA plays a regulatory role in E. coli, we used two-dimensional gel electrophoresis to compare the distribution of E. coli proteins in hflA+ and hflA- cells. We found at least 13 proteins that are present in hflA- strains, but absent or very low in hflA+ strains. This observation indicates that HflA might be involved in regulation of a large class of E. coli proteins. Because of prior work implicating the Crp/cAMP system in Hfl-mediated regulation of lambda, we also studied the distribution of E. coli proteins in cya- strains unable to synthesize cAMP. Some of the same proteins found in hflA- are elicited by the addition of cAMP to cya- cells.

Bacterial Proteins↗

Delta hepatitis virus infection in China.

To assess the prevalence, epidemiological features and prognostic implications of hepatitis D (Delta) in Sichuan Province, The People's Republic of China, 649 sera (515 from HBsAg positive patients and 134 from HBsAg negative subjects) were tested by radioimmunoassay (RIA) for antibody to the hepatitis D virus (anti-HD). Forty-seven sera (7.2%) showed some degree of reactivity. Serial dilutions of these sera indicated that prozoning was not responsible for the equivocal results. Thirty-four of the 47 sera were submitted under code to a second laboratory for independent analysis. According to those results anti-HD antibodies were detected in four of these sera. The overall prevalence of anti-HD in the HBsAg positive patients therefore was 0.8% (4/515). On the basis of clinical, biochemical and histological data 427 HBsAg positive sera were further divided into acute Type B hepatitis, chronic Type B hepatitis, healthy carrier state and hepatocellular carcinoma (HCC) subgroups. Two of 65 (3.1%) anti-HD positive sera belonged to the acute Type B hepatitis group; one of 104 (0.9%), the chronic Type B hepatitis group and one of 246 (0.4%), the healthy carrier group. No antibody was detected in sera from 12 HBsAg positive HCC patients. All HBsAg negative patients were negative for anti-HD antibody. The results of this study indicate that despite a high prevalence of hepatitis B virus infection, positive serology for delta virus is uncommon in Sichuan Province, The People's Republic of China.

Adolescent↗