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Biomedical subjects

N Chin

Publications and source records attributed to N Chin.

At least 19 recordsLinked to original sources
PubMed1999

Female development in mammals is regulated by Wnt-4 signalling.

In the mammalian embryo, both sexes are initially morphologically indistinguishable: specific hormones are required for sex-specific development. Mullerian inhibiting substance and testosterone secreted by the differentiating embryonic testes result in the loss of female (Mullerian) or promotion of male (Wolffian) reproductive duct development, respectively. The signalling molecule Wnt-4 is crucial for female sexual development. At birth, sexual development in males with a mutation in Wnt-4 appears to be normal; however, Wnt-4-mutant females are masculinized-the Mullerian duct is absent while the Wolffian duct continues to develop. Wnt-4 is initially required in both sexes for formation of the Mullerian duct, then Wnt-4 in the developing ovary appears to suppress the development of Leydig cells; consequently, Wnt-4-mutant females ectopically activate testosterone biosynthesis. Wnt-4 may also be required for maintenance of the female germ line. Thus, the establishment of sexual dimorphism is under the control of both local and systemic signals.

Animals↗
PubMed1999

Management of heel pain syndrome with acetic acid iontophoresis.

This study was undertaken to determine the effectiveness of acetic acid iontophoresis in the treatment of heel pain. Thirty-five patients with chronic heel pain were treated with acetic acid iontophoresis over a 4-year period. Ninety-four percent of patients had complete or substantial relief of heel pain after an average of 5.7 sessions of acetic acid iontophoresis over an average period of 2.8 weeks. Heel pain levels were rated from 0 to 10, with 10 representing the most severe pain. Heel pain prior to iontophoresis treatment received an average rating of 7.5; by the end of therapy, the average rating had decreased to 1.8. At an average follow-up time of 27 months, heel pain levels averaged 0.64, indicating continued reduction in heel pain. Ninety-four percent of participants said that they would recommend acetic acid iontophoresis to someone with similar heel pain.

Acetic Acid↗
PubMed1997

Pigmented sweat gland tumor mimicking melanoma.

Eccrine poroma, a common adnexal neoplasm, usually presents as a solitary, smooth, flesh-colored nodule on the foot or hand. Eccrine porocarcinoma is extremely rare and much more variable in its morphology and location. Both tumors can contain melanocytes and melanin. We describe a patient with an enlarging, eroded brownish black nodule on his shoulder. Examination of a biopsy specimen showed it to be derived from acrosyringium and to contain abundant melanin and scattered dendritic melanocytes. Eccrine poroma and porocarcinoma should be considered in the clinical differential diagnosis of pigmented tumors.

Acrospiroma↗
PubMed1996

Identification of a locus involved in the utilization of iron by Actinobacillus pleuropneumoniae.

The cloned afu locus of Actinobacillus pleuropneumoniae restored the ability of an Escherichia coli K-12 mutant (aroB) to grow on iron-limited media. DNA sequence analysis of the fragment showed that there are three genes designated afuA, afuB and afuC (Actinobacillus ferric uptake) that encode products similar to the SfuABC proteins of Serratia marcescens, the HitABC proteins of Haemophilus influenzae, the FbpABC proteins of Neisseria gonorrhoeae and the YfuABC proteins of Yersinia enterocolitica. The three genes encode a periplasmic iron-binding protein (AfuA), a highly hydrophobic integral cytoplasmic membrane protein with two consensus permease motifs (AfuB) and one hydrophilic peripheral cytoplasmic membrane protein with Walker ATP-binding motifs (AfuC), respectively. This system has been shown to constitute a periplasmic binding protein-dependent iron transport system in these organisms. The afuABC operon is locating approximately 200 bp upstream of apxIC gene, but transcribed in opposite direction to the ApxI-toxin genes.

Actinobacillus pleuropneumoniae↗
PubMed1995

Near-hanging caused by a toy necklace.

Hanging injuries and fatalities are rare among children and are usually unintentional. In this report we describe a 23-month-old girl who almost died when she accidentally hanged herself with a popular toy necklace, and we discuss recent epidemiological trends in accidental strangulations among children. This case emphasizes the need for increased awareness among consumers, health care providers, and product manufacturers about the dangers of toys such as the one described here.

Accidents, Home↗
PubMed1995

Sequence analysis of leukotoxin secretion determinants from a Pasteurella haemolytica-like organism.

The pHLBD genes encoding the secretion functions for the 105 kDa RTX leukotoxin of Pasteurella haemolytica-like (PHL) organism has been cloned and sequenced. Like analogous genes from other RTX determinants, the pHLBD genes lie immediately downstream from the leukotoxin structural gene, pHLA. Although isolated from a diverse group of gram-negative organisms, the pHLBD genes and the characterized RTX BD genes from other organisms exhibit a high degree of homology at both the DNA and predicted amino acid sequence levels. We have previously reported the cloning of the leukotoxin gene (pHLCA) (Chang et al., Infect. Immun. 61:2089-2095), which encodes a 105-kda polypeptide with cytotoxic activity. DNA sequence analysis of the pHLBD genes shows 83.93% and 86.05% homologous to that of P. haemolytica IktBD genes, respectively.

ATP-Binding Cassette Transporters↗
PubMed1994

Comparison of employees' white blood cell counts in a petrochemical plant by worksite and race.

To determine if employment within a petrochemical plant's quality control (QC) laboratory had any significant effect on the hematopoietic system, and in specific, the white blood cell (WBC) counts, all employees of the QC laboratory were evaluated retrospectively. Trend analysis, linear regression, and Students t tests were performed on all employees of the QC laboratory and on a simple random sample of the rest of this Caribbean petrochemical plant's male employees. Trend analyses revealed a downward trend in 82.6% of the QC laboratory workers and 76.7% in other plant workers. Linear regression and t tests revealed no statistically significant difference by worksite but a significant difference between blacks and whites. The result of the findings of the QC laboratory workers was consistent with that expected in both plant employees and the US general population. A recommendation is made that the Occupational Safety and Health Administration (OSHA) reconsider its WBC cutoff level in the benzene standard.

Adult↗
PubMed1992

The activity of metal compounds against aerobic and anaerobic bacteria.

We evaluated the antimicrobial activity of two metal compounds, JM-1397 (OsO2[xylyl]2) and JM-2469 (AuCl[S2CPEt3]). Both inhibited methicillin-susceptible and methicillin-resistant Staphylococcus aureus at concentrations of 0.5-2 micrograms/ml, with a minimum inhibitory concentration (MIC90) of 1 microgram/ml for JM-1397 and 0.5 microgram/ml for JM-2469. Similar concentrations inhibited methicillin-susceptible and -resistant coagulase-negative staphylococci (S. epidermidis, S. haemolyticus, and S. saprophyticus). JM-2469 inhibited group A, B, C, F, and G beta-hemolytic streptococci and viridans group streptococci at 1-8 micrograms/ml (MIC90 4 micrograms/ml) but Enterococcus faecalis and E. faecium had MICs of 8-16 micrograms/ml. JM-1397 had MICs for these organisms of greater than 64 micrograms/ml. Bacteroides fragilis, other Bacteroides, and Clostridium species were inhibited by less than or equal to 0.12-4 micrograms/ml (MIC90, 0.5 microgram/ml). MICs of both compounds for Enterobacteriaceae and Pseudomonas spp. were greater than 64 micrograms/ml. These studies show that osmium and gold compounds have potential as topical agents against Gram-positive and anaerobic species.

Anti-Bacterial Agents↗
PubMed1989

Differences in portal hemodynamics in cirrhosis and idiopathic portal hypertension.

A comparative study of portal hemodynamics was made in 79 cirrhotics (24 cirrhotics with a large spleen greater than or equal to 500 cm3 in volume, 55 cirrhotics with a spleen less than 500 cm3 in volume), 22 patients with idiopathic portal hypertension, and 63 healthy adults who served as the control for portal and splenic venous flows. Portal and splenic venous flows were significantly increased in the group order of the cirrhosis without splenomegaly group, the cirrhosis with splenomegaly group, and idiopathic portal hypertension group. Intrahepatic shunt index was significantly greater in the cirrhosis with splenomegaly group than in the cirrhosis without splenomegaly group, and it was negligible in the idiopathic portal hypertension group. Portal vein pressure was significantly elevated in the cirrhosis with splenomegaly group than in the cirrhosis without splenomegaly and idiopathic portal hypertension groups. Postsinusoidal resistances were significantly greater in the two groups of cirrhosis than in the idiopathic portal hypertension group, whereas presinusoidal resistance was significantly greater in the idiopathic portal hypertension group than in the two groups with cirrhosis. It is concluded that these differences are inconsistent with the view that cirrhosis with splenomegaly comes from idiopathic portal hypertension.

Female↗
PubMed1988

Intestinal obstruction in patients with ovarian cancer. Variables associated with surgical complications and survival.

Intestinal obstruction is frequently encountered in patients with ovarian cancer. Surgical correction of intestinal obstruction may allow the prolonged survival of some patients. We identified prognostic factors associated with operative complications and postoperative survival. Multiple preoperative, intraoperative, and postoperative variables were considered. In addition, a previously published prognostic index was evaluated. Statistical assessment developed a model that demonstrated that the clinical assessment of tumor status, the serum albumin level, and the nutrition score were variables significantly associated with postoperative survival. The amount of residual ovarian cancer at the completion of bowel obstruction surgery was also significantly associated with postoperative survival. This information may aid in the preoperative selection of patients who might benefit from surgical correction of intestinal obstruction.

Aged↗
PubMed1988

Renal metastases of gestational trophoblastic disease: a report of eight cases.

Between 1968-1984, eight women with renal metastases of gestational trophoblastic disease were treated at the Southeastern Regional Trophoblastic Disease Center. Two (1.3%) of 154 patients referred for primary therapy and six (14%) of 42 patients referred for secondary therapy of metastatic gestational trophoblastic disease had renal metastases. All eight had coexistent pulmonary metastases. Four had central nervous system and other systemic metastases. All had high-risk metastatic gestational trophoblastic disease by assessment of individual risk factors and analysis of a prognostic index score. Three women with limited systemic tumor burden are alive after receiving multiagent chemotherapy and nephrectomy.

Female↗
PubMed1988

Role of intrahepatic portal-systemic shunts in the reduction of portal blood supply to liver cells in cirrhosis.

To assess the role of intrahepatic portal-systemic shunts in the reduction of portal blood supply to the liver cells in cirrhosis, we measured portal venous flow (blood flow in the portal trunk) by the pulsed Doppler flowmeter and intrahepatic portal-systemic shunt index from the counts over the lungs and liver in both the anterior and posterior projections after instillation of 99mTc-macroaggregated albumin in the portal vein, and calculated portal sinusoidal flow (blood flow into the sinusoids via the portal vein), using the equation, (sequence; see text) in 47 patients with posthepatitic cirrhosis, and measured portal venous flow in 63 healthy adults in whom portal sinusoidal flow should be comparable to portal venous flow. Portal sinusoidal flow was significantly reduced in cirrhotics with an intrahepatic portal-systemic shunt index averaging 24%, whereas portal venous flow was similar in the cirrhotics and control. There was a significant inverse correlation between intrahepatic portal-systemic shunt index and portal sinusoidal flow. When cirrhotics were divided into three stages, based on Child's grading, intrahepatic portal-systemic shunt index was significantly increased in the group order of Child's A (8 +/- 9%), Child's B (27 +/- 22%), and Child's C patients (46 +/- 19%), and portal sinusoidal flow was decreased in the same order. Portal sinusoidal flow was significantly reduced in Child's B and Child's C patients, but not in Child's A patients, compared with the control. In conclusion, intrahepatic portal-systemic shunts may play a role, at least in part, in the reduction of portal blood supply to the liver cells in patients with advanced stage of posthepatitic cirrhosis when large intrahepatic portal-systemic shunts develop.

Adult↗
PubMed1987

Quantitative aspects of portal-systemic and arteriovenous shunts within the liver in cirrhosis.

To estimate vascular changes in chronic liver disease, we quantitated intrahepatic arteriovenous and portal-systemic shunts in 12 patients with cirrhosis and arteriovenous shunts alone in 4 patients with cirrhosis. An index was obtained for intrahepatic arteriovenous shunts by instilling technetium 99m-macroaggregated albumin into the proper hepatic artery and portal-systemic shunts, by the same procedure done in the portal trunk, near the porta hepatis on different days. Counts were taken over the liver and both lungs in the anterior as well as the posterior view for calculation of the shunt index: cpm in lungs divided by cpm in liver and lungs X 100%. In the 12 patients with cirrhosis in whom both shunts were measured, intrahepatic arteriovenous shunting was significantly lower compared with intrahepatic portal-systemic shunting (1.4% +/- 1.1% vs. 36.0% +/- 29.0%, p less than 0.001). Thus, it seems that in patients with cirrhosis, the development of intrahepatic arteriovenous shunts is not as great as that of portal-systemic shunts, which were found in this study to be considerable and variable in degree.

Adult↗
PubMed1987

Total parenteral nutrition in poor prognosis gestational trophoblastic disease.

From 1978 through 1984, 35 women received therapy for poor prognosis gestational trophoblastic disease (GTD) at Duke University Medical Center. Total parenteral nutrition (TPN) was utilized in nine patients (26%) for reasons including inadequate oral intake, nutritional depletion, and/or bone marrow suppression. Overall survival with follow-up ranging from 12 to 78 months was 88% for the TPN group and 70% for the non-TPN group (P = 0.38). Median duration of TPN therapy was 4 weeks (2-46 weeks). Intensity of therapy was comparable between the groups. Median weight gain of 0.15 kg/week for the TPN group was significantly greater than the 0.18/kg/week weight loss in the non-TPN group (P less than 0.001). Severe nutritional depletion represented by both low serum albumin (less than or equal to 2.5 gm/dl) and weight loss greater than or equal to 10% had a higher mortality rate than when only one of these factors existed (P = 0.006). Future studies need to further define the proper role of TPN in patients with poor prognosis GTD especially in those with severe nutritional deficits.

Adolescent↗
PubMed1987

In vitro fertilization and embryo transfer in patients with one ovary.

The purpose of this investigation was to compare follicular response and pregnancy rates in patients with one and two ovaries who have undergone in vitro fertilization (IVF). No statistically significant difference was found in serum estradiol levels on the day of human chorionic gonadotropin administration, mean number of follicles (greater than 15 mm), mean total number of oocytes recovered, mean number of mature oocytes recovered, or number of pregnancies per transfer. The total number of oocytes recovered in the one- and two-ovary groups was 47 and 123, respectively. There was a significantly greater mean number of immature oocytes recovered (1.5 +/- .03 versus 0.5 +/- 0.2, P less than 0.01) and embryos transferred (2.7 +/- 0.3 versus 1.7 +/- 0.3, P less than .04) in patients with two ovaries. Though not statistically significant, a trend was noted in the two-ovary group for a greater number of pregnancies per transfer (9:25 versus 2:14). The authors conclude that single-ovary patients may have a reduced outcome with IVF compared with patients with two ovaries.

Adult↗
PubMed1986

Clinical and portal hemodynamic features in cirrhotic patients having a large spontaneous splenorenal and/or gastrorenal shunt.

Clinical and portal hemodynamic features in 28 cirrhotic subjects with a large spontaneous spleno- and/or gastrorenal shunt were studied in comparison with 30 control cirrhotic cases without such collaterals. Forty-six percent of the former had chronic hepatic encephalopathy, but none of the latter was encephalopathic. These patients with large renal shunts were divided into those with and those without encephalopathy. Large esophageal varices were significantly less common in patients with a large shunt and encephalopathy compared with those who had a large shunt but no encephalopathy, and the control. But there was no significant difference of past variceal bleeding among these three groups. In all those with encephalopathy, part of superior mesenteric venous blood was shunting through these collaterals into the left renal vein or inferior vena cava, but the same was not demonstrable in patients with a large shunt and no encephalopathy and control cirrhotics. In the chronic encephalopathic, portal venous flow was estimated to be less than one-half of that in control cirrhotics, and the portion of superior mesenteric venous blood that was flowing hepatofugally through a large shunt into the left renal vein seemed about the same or greater than the portal venous flow. Thus, a large spontaneous spleno- and/or gastrorenal shunt might prevent development of large esophageal varices but not variceal hemorrhage and it increased a risk of chronic hepatic encephalopathy.

Adult↗