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Biomedical subjects

C H Hsu

Publications and source records attributed to C H Hsu.

At least 19 recordsLinked to original sources
PubMed1998

Prenatal and neonatal intussusception.

Intussusception found in the 1st month of life is rare and usually discussed as one entity, neonatal intussusception, but in fact, includes the intussusceptions occurring both prenatally and neonatally, of which the clinical presentations and results are different. Four full-term babies with prenatal intussusception presenting as intestinal atresia (IA) and three premature babies with neonatal intussusception mimicking necrotizing enterocolitis (NEC) are presented. Prenatal intussusception, as one of the causes of IA produces prominent signs of intestinal obstruction immediately after birth. Preoperative evaluation usually fails to yield a definitive diagnosis, but surgery is usually performed in time and is successful. In neonatal intussusception, full-term infants usually have a pathological lead point and the colon is almost always involved. A barium enema is thus useful in diagnosis. Premature babies, on the other hand, rarely have a colonic component, and the clinical features are insidious and similar to NEC. This results in diagnostic confusion that may lead to a dangerous delay in appropriate surgical correction. A high level of suspicion about this condition in cases diagnosed presumptively with NEC is important. Serial abdominal sonograms may be helpful in the early diagnosis of neonatal intussusception.

Fatal Outcome↗
PubMed1998

Alterations of RET oncogene in human adrenal tumors.

Previous studies have revealed specific activations of the RET oncogene in multiple endocrine neoplasia type 2 (MEN 2) and thyroid tumors. To understand the role of the RET proto-oncogene activation in sporadic adrenal tumors, we analyzed the alterations of the RET proto-oncogene in the cysteine-rich extracellular domain (exons 6 and 10), the terminal region of the extracellular domain and transmembrane domain (exon 11) and the tyrosine kinase domain (exons 12-17) in 35 cases of adrenal tumors (including 18 Conn's syndrome, 3 Cushing's syndrome, 2 non-functional adrenocortical tumor and 12 pheochromocytomas by polymerase chain reaction-single strand conformational polymorphism and sequencing methods. One case with pheochromocytoma and one with Conn's syndrome had point mutation. We also detected the rearrangement of the RET gene by reverse transcription-polymerase chain reaction and Southern hybridization. One case with Conn's syndrome and one with Cushing's syndrome were found to harbor RET/PTC1 (RET tyrosine kinase domain rearranged with H4 gene). The above results indicate that RET proto-oncogene mutations and RET/PTC1 are involved in the pathogenesis of sporadic adrenal tumors. Mutations at codon 634 of the RET gene were also found in adrenal tumors. This suggests that the RET oncogene may also play a role in the tumorigenesis of adrenal tumors, and this possibility requires further investigation.

Adrenal Gland Neoplasms↗
PubMed1998

DQA1*Arg52,DQB1*nonAsp57, and DRB1*04 genotypes in Chinese children with insulin-dependent diabetes mellitus.

Ethnic comparisons are extremely important and useful for studying the HLA component involved in insulin-dependent diabetes mellitus (IDDM) predisposition. To date there have been only a few reports on the association of HLA loci and IDDM in Chinese. We report here a study on DQA1*Arg52, DQB1*nonAsp57, and DRB1*04 in IDDM children and control adults among Han Chinese living in Taiwan. One hundred and fourteen unrelated children (62 boys) with IDDM were studied. Their ages at diagnosis were between 0.3 and 15.0 years (6.8 +/- 3.6 years). The control population consisted of 120 randomly selected normal adults. DQA1*Arg52(+/+), DQB1*nonAsp57(+/+), and DRB1*04(+/-) were associated with IDDM (RR = 11.50, 2.21, and 2.82; p = 1.11 x 10(-15), 2.84 x 10(-3), and 1.98 x 10(-4), respectively). DQA1*Arg52, DQB1*nonAsp57, and DRB1*04 conferred risks for IDDM (RR = 12.79, 7.11, and 2.83; pc = 8.22 x 10(-4), 5.35 x 10(-3), and 5.68 x 10(-4), respectively). Combinations of DQA1*Arg52 and DRB1*04 conferred the highest risk for IDDM (RR = 19.64, pc = 5.4 x 10(-5)). DQA1*Arg52 was associated with IDDM in subjects with DQB1*nonAsp57+ (RR = 14.87, pc = 2.41 x 10(-4)) and DQB1*nonAsp57 was also associated with IDDM in subjects with DQA1*Arg52+ (RR = 8.41, pc = 1.54 x 10(-3)), suggesting that DQA1*Arg52 and DQB1*nonAsp57 are interacting. This study demonstrates that DQA1*Arg52, DQB1*nonAsp57, and DRB1*04 confer susceptibility for IDDM to Chinese children. A combination of DQA1*Arg52 and DRB1*04 confers the highest risk and it is suggested that a susceptibility gene might be situated between DQA1*Arg52 and DRB1*04 or both are synergistic. There is an interaction between DQA1*Arg52 and DQB1*nonAsp57 and homozygosity for DQA1*Arg52/DQB1*nonAsp57, which encodes four susceptibility DQ heterodimers, confers a high risk.

Adolescent↗
PubMed1998

Atrial flutter in the neonate and early infancy.

Atrial flutter is a rare arrhythmia in the neonate and early infancy. We retrospectively reviewed the clinical presentations, treatment and outcome of seven patients who presented clinically with atrial flutter. The age of onset ranged from 1 day to 3 months. Atrial flutter was diagnosed in the first 3 days of life in 4. Three cases presented as atrial flutter with 2:1 atrioventricular conduction and the remaining 4 with variable AV block. Heart failure was present in 3 patients and 6 patients showed normal intracardiac structure on echocardiography. Electrical cardioversion was attempted as the first treatment in 4 cases, followed by digoxin in three of the four. Digoxin was given as an initial therapy in 2 patients. One patient recovered spontaneously without treatment. In the 6 patients who received therapy, 5 converted to normal sinus rhythm within 2 days. The remaining patient had ventricular ectopic beats for about 4 months. Only 2 cases were maintained on oral digoxin for at least 4 months after discharge. No patient had a recurrence of atrial flutter during the follow-up period which ranged from 6 months to 7 years. We conclude that there is a good long-term prognosis for atrial flutter in the neonate. Digoxin and DC cardioversion may be effective as initial therapy. Long-term digoxin prophylaxis after conversion to sinus rhythm may be not necessary.

Age of Onset↗
PubMed1998

Inhibition of calcitriol-induced monocyte CD14 expression by uremic toxins: role of purines.

End-stage renal disease is associated with a defect in immunologic functions. Previous studies have demonstrated that uremic ultrafiltrate (UUF) contains factors that suppress calcitriol synthesis and its biological actions. In the present study, the effect of UUF on basal and calcitriol-induced membrane bound CD14 expression of monocytes activated by phorbol 12-myristate 13-acetate was evaluated. CD14 acts as a receptor for the complexes of lipopolysaccharide and lipopolysaccharide-binding protein. Monocytes isolated from normal donors were used for the assay of monocyte CD14 expression. A calcitriol induced rise in monocyte CD14 expression (1966+/-423 to 2421+/-436 fluorescence intensity) was found. However, UUF not only suppressed basal CD14 expression of monocytes (from 1966+/-423 to 1240+/-203, P < 0.05) but also significantly blunted calcitriol-induced CD14 expression (from 2421+/-436 to 1744+/-229, P < 0.05). HPLC fractionated UUF collected from 8 to 16 min (fraction 1, F1) and from 25 to 40 min (fraction 3, F3) also significantly suppressed the expression of CD14. Because purine derivatives coeluted within F1, their effect on monocyte CD14 expression was also tested. Uric acid, xanthine, and hypoxanthine was found to suppress basal as well as calcitriol-induced CD14 expression of monocytes in a dose-dependent manner. In conclusion, UUF contains factors that impair calcitriol activated function of monocytes.

Calcitriol↗
PubMed1997

Frequency of associated anomalies in congenital hypoplasia of depressor anguli oris muscle: a study of 50 patients.

Aside from congenital heart disease, anomalies associated with unilateral hypoplasia of the depressor anguli oris muscle have not been well-documented in large series. We evaluated the associated anomalies in 50 infants or children with this disorder (male:female = 2:1) and found accompanying anomalies in 35 (70%) of 50 cases. They included anomalies of the head and neck (48%), heart (44%), skeleton (22%), genitourinary tract (24%), central nervous system (10%), gastrointestinal tract (6%), and miscellaneous minor anomalies (8%). Nearly half of our cases (22/50) had at least 2 associated systemic anomalies. Failure to thrive and psychomotor retardation were found in 5 (10%) and 3 (6%) patients, respectively, on follow-up. Three infants died neonatally of severe heart disorders, and the other one died of central nervous system anomalies. The above findings indicate that a thorough search for associated anomalies, particularly in the cardiovascular system, should be performed in all newborns with asymmetric crying face.

Abnormalities, Multiple↗
PubMed1997

Functional characterization of a chicken major histocompatibility complex class II B gene promoter.

A 0.7 kilobase (kb) DNA fragment from the 5' flanking region of a chicken major histocompatibility complex (MHC) class II B gene was cloned into chloramphenicol acetyltransferase (CAT) reporter vectors and was transfected into a chicken macrophage cell line that expresses a low level of MHC class II antigens. Positive orientation-dependent promoter activity of the chicken DNA was evident in a reporter construct containing an SV40 enhancer. Deletion analysis of this 0.7 kb DNA fragment revealed a short fragment in the 3' end that was crucial for the promoter function and negative regulatory elements (NRE) located further upstream. The conserved MHC class II X and Y boxes did not have a significant effect on promoter activity. Sequence analysis of the 0.7 kb class II B gene upstream region suggests possible involvement of interferon (IFN), E twenty-six specific (ETS)-related proteins, and other factors in regulating this promoter. A chicken T-cell line culture supernatant increased surface expression of MHC class II antigens, as well as class II promoter activity, in this macrophage cell line. This first functional characterization of a chicken MHC class II B gene promoter will aid in understanding the regulatory mechanisms that control the expression of these genes.

Animals↗
PubMed1997

Are we mismanaging calcium and phosphate metabolism in renal failure?

Secondary hyperparathyroidism and renal osteodystrophy are the consequences of abnormal calcium, phosphate, and calcitriol metabolism ensuing from renal failure. Evidence suggests that calcium balance tends to become negative as we grow older than 35 years of age; however, the current dialysis modalities provide patients regardless of age with excessive calcium during dialysis. Administration of calcitriol in the management of hyperparathyroidism further increases the calcium and phosphate absorption. Furthermore, the current thrice-weekly renal replacement therapies fail to remove the daily absorbed phosphate, and we have to use calcium carbonate as a primary phosphate-binding agent to reduce intestinal phosphate absorption. The large calcium mass transfer and phosphate retention could lead to soft tissue calcification, especially in older end-stage renal disease (ESRD) patients. Consequently, only by maintaining a negative calcium balance during renal replacement therapy can we safely use calcitriol and calcium carbonate for the management of secondary hyperparathyroidism. Recent studies have indicated that phosphate restriction alone independent of plasma calcitriol or calcium can lower plasma parathyroid hormone (PTH) in renal failure and prevent hyperplasia of parathyroid glands. Therefore, phosphate control perhaps is the most important means to prevent secondary hyperparathyroidism. Previous studies have shown that ferric compounds are potent phosphate-binding agents; hence, these compounds warrant further trial in the management of phosphate metabolism in renal failure.

Adult↗
PubMed1997

Characterization of DNA adducts formed by cyclopenta[cd]pyrene epoxide.

Cyclopenta[cd]pyrene (CPP) is a ubiquitous environmental pollutant whose 3,4-epoxide (CPPE) is generally regarded as its ultimate carcinogenic metabolite. The present study was undertaken to determine the structures of major DNA adducts formed by CPPE in vitro. Incorporation of specific radiolabeled bases into calf thymus DNA prior to reaction with CPPE demonstrated that the major adducts were formed by guanine, while minor adducts were formed by adenine and cytosine. Unmodified DNA was reacted with [3H]CPPE and the deoxynucleoside adducts obtained were compared chromatographically with the products obtained by reaction of CPPE with 2'-deoxyguanosine (dGuo). Two dGuo adducts from the latter reaction were identified by 1H-NMR, fast atom bombardment mass spectrometry, and circular dichroism as diastereoisomers of cis-3-(deoxyguanosin-N2-yl)-4-hydroxy-3,4-dihydroCPP. Other products that may have included the isomeric trans-N2-dGuo adduct were formed in the reaction. The major adduct fraction in the DNA digest, accounting for over 70% of the total, was chromatographically indistinguishable from the two cis dGuo-N2 adducts. A second DNA adduct fraction was observed, which appeared also to be formed by reaction with guanine as indicated by experiments in which DNA containing [3H]guanine was reacted with unlabeled CPPE. The results confirm that guanine is the major target in DNA for reaction with CPPE and are the first proof of structure for a CPPE-deoxynucleoside adduct.

Animals↗
PubMed1997

Effect of glyoxylate on the function of the calcitriol receptor and vitamin D metabolism.

The biological action of calcitriol is mostly mediated through the interaction of the calcitriol receptor (VDR) with vitamin D response elements (VDREs) of target genes. These interactions produce special proteins that carry out the biological activities of calcitriol. Recently, we showed that the interaction of VDRs with VDREs is inhibited by uremic toxins. We hypothesize that uremic toxins that contain aldehyde or ketone groups potentially could form Schiff bases with lysine residues of the VDR DNA binding domain and inhibit VDR interaction with VDREs. We therefore chose glyoxylate, a compound which has an aldehyde group, to test this hypothesis. In vitro glyoxylate inhibited VDR binding to the osteocalcin and osteopontin VDREs as assessed by electrophoretic mobility shift assay and the inhibition was reversed when glyoxylate was preincubated with lysine. Further, this chemical compound also blocked the induction of chloramphenicol acetyltransferase (CAT) enzyme induced by calcitriol in cells transfected with a calcitriol responsive CAT reporter gene. Since induction of 24-hydroxylase synthesis is a VDR regulated process, we also studied the effect of glyoxylate on the activity of intestinal 24-hydroxylase in rats. This enzyme activity was suppressed in rats infused with glyoxylate. Taken together, our study suggests that glyoxylate could inhibit the interaction of VDR with VDREs and alter the biological action of calcitriol.

Animals↗
PubMed1997

Effect of glucose on the function of the calcitriol receptor and vitamin D metabolism.

The genomic action of calcitriol is mediated through the interaction of the calcitriol receptor (VDR) with vitamin D response elements (VDREs) of the target genes. It has been proposed that chemicals capable of Schiff base formation with the VDR potentially could alter the physiological function of VDR and calcitriol metabolism. Since glucose has been shown to form Schiff bases with proteins, we tested the hypothesis that glucose could influence the function of VDR and thereby alter calcitriol metabolism. Glucose 6-phosphate inhibited VDR binding to the osteocalcin VDRE and chemically modified the DNA binding domain or the dimerization domain of the VDR in vitro. Further, glucose also blocked the production of chloramphenicol acetyltransferase (CAT) enzyme induced by calcitriol in cells transfected with a constructed VDRE attached to a CAT reporter gene. Hyperglycemia induced by glucose infusion or by streptozotocin in normal rats significantly reduced intestinal 1 alpha, 25-dihydroxyvitamin D-24-hydroxylase activity. Taken together, these findings are consistent with the hypothesis that glucose could interact with the VDR to impair its DNA binding and function within cells.

Animals↗
PubMed1996

Ricin depresses cardiac function in the rabbit heart.

Ricin, at toxic glycoprotein from the castor bean, causes myocardial hemorrhage and a decrease in blood pressure. We studied the effects of ricin on myocardial function in the isolated rabbit heart. Rabbits were given 0.22 micrograms/kg of ricin i.v. and 48 hr later, the heart was isolated and retrogradely perfused through the aorta with Tyrode's solution. A latex balloon was inserted into the left ventricle and isovolumic left ventricular function curves were generated. Left ventricular developed pressure (LVDP), heart rate, coronary artery flow, left ventricular end diastolic pressure, myocardial oxygen consumption, oxygen extraction (a - vO2), and contractility (+dp/dt) were measured over a range of left ventricular volumes. Dose-response curves to isoproterenol (10(-9)-10(-8) M) and phenylephrine (10(-9)-10(-6) M) were also obtained. Compared to the control group, ricin pretreatment markedly decreased ventricular compliance (p < 0.01), diminished maximum left ventricular developed pressure (p < 0.05), and reduced maximal +dp/dt (p < 0.05). Myocardial oxygen consumption, heart rate, electrocardiographic PR, QRS, and QT intervals were not different in control and ricin treatment groups. Ricin did not significantly alter the inotropic or chronotropic responses to isoproterenol and phenylephrine. The results from the binding studies showed that ricin neither reduced beta-adrenergic receptor numbers nor altered the dissociation constant. thus, ricin reduced both systolic (LVDP and +dp/dt) and diastolic (compliance) left ventricular functions, perhaps due to increased vascular permeability, without altering responses to the alpha- and beta-adrenoceptor agonists phenylephrine and isoproterenol.

Adrenergic beta-Agonists↗
PubMed1996

Pancreatitis in children--experience with 43 cases.

UNLABELLED: Pancreatitis in children is not common and can be associated with severe morbidity and mortality. We encountered 43 children, ranging in age from 2 to 18 years, with pancreatitis over the past 10 years. The diagnosis of pancreatitis was made in those patients who showed: (1) significant intra-operative pathology or; (2) clinical findings of pancreatic inflammation and laboratory confirmation. More than one third (16 cases) of the cases were due to trauma, other causes included systemic disease (10), structural disease (8), and toxins or drugs (4). Five cases were classified as idiopathic. Most of the patients presented with abdominal pain (95%) and vomiting (56%). Jaundice was found in 7 patients and an abdominal mass in 2. Morbidity included pseudocyst (10), relapse (4), hyperglycaemia (4) and miscellaneous problems. Eight (50%) of the patients with trauma and 6 (86%) of the patients with structural diseases required surgery. Other patients were managed conservatively with bowel rest, gastric decompression, intravenous fluid and total parenteral nutrition. One case had a fatal outcome. All the survivors did well in long term follow up. Relevant literature has been reviewed and the sensitivity of various diagnostic modalities compared and discussed. A lesser known association between pancreatitis and structural anomalies such as choledochal cyst is discussed. To our knowledge, the present review is the first on pancreatitis in Chinese children. CONCLUSION: Pancreatitis can occur from a wide variety of causes and may result in severe complications. Early diagnosis, close monitoring and aggressive intervention are mandatory to reduce morbidity and mortality.

Abdomen, Acute↗
PubMed1996

The integrated design of mechanical bi-leaflet prosthetic heart valves.

A flow model utilizing an irrotational, inviscid algorithm of vortex-ring elements simulating the leaflets and source/sink elements simulating the aortic root coupled with a boundary layer model has been developed to model the internal flow phenomena of bi-leaflet mechanical heart valves implanted in the aortic root. The inviscid representation evaluates the aerodynamic lift, the induced drag, the pitching moment and flow velocity along the leaflet surface thus providing data for evaluating the boundary-layer thickness, the shear stress and flow separation point by the boundary layer theory. Full integration with the geometry enables immediate updates of the flow solution when changes in geometry have been made. It is shown that the effects of the internal flow domain model are necessary in the correct evaluation of lift and drag for subsequent dynamic analysis. The environment presented provides for the ability to produce significant and immediate design changes so that crucial decisions may be made whilst still within the software design loop. New designs are shown along with data for the improved flow model.

Algorithms↗
PubMed1996

Dynamic analysis and geometry models for the design of bi-leaflet prosthetic mechanical heart valves.

This paper provides new geometry definitions for the axi-symmetric stiffening (or sewing) ring, as part of a bi-leaflet prosthetic heart valve, and presents a dynamic behaviour analysis of the leaflet. An optimal stiffening ring geometry may be constructed by considering the point of flow separation on the stiffening ring (measured in the downstream coordinate), the effective orifice area of the stiffening ring and the associated dynamic behaviour of the leaflet. The dynamic model is accomplished by utilizing a second-order rotating system to simulate the opening and closing characteristics of the leaflet. The moments due to the aerodynamic loads are evaluated from an irrotational inviscid flow model, coupled with boundary layer theory, modelling the internal flow phenomena of the bi-leaflet heart valve implanted in the aortic root. It has been shown that this internal flow model provides the correct evaluation of lift and induced drag and the subsequent dynamic characteristics.

Algorithms↗
PubMed1996

Effect of Schiff base formation on the function of the calcitriol receptor.

The genomic action of calcitriol is mediated through the interaction of the calcitriol receptor (VDR) with vitamin D response elements (VDREs) of the target genes. We have shown that the interaction of VDRs with VDREs is inhibited by uremic toxins. We hypothesize that uremic toxins form Schiff bases with the lysine residues of the VDR DNA binding domain and inhibit the VDR interaction with the VDRE. In this study, pyridoxal 5'-phosphate was used as a probe to test Schiff base formation as the inhibitory mechanism, since it forms Schiff bases with steroid receptors. Pyridoxal 5'-phosphate inhibited the VDR binding to the VDREs and chemically modified the DNA binding domain of the VDR in vitro. The inhibition was reversed when pyridoxal 5'-phosphate was preincubated with lysine. Further, this chemical agent also blocked the production of chloramphenicol acetyltransferase (CAT) enzyme induced by calcitriol in cells transfected with a constructed VDRE attached to a CAT reporter gene. This finding is consistent with the hypothesis that pyridoxal 5'-phosphate could interact with the VDR and impair its DNA binding within cells. Since induction of 24-hydroxylase synthesis is a receptor mediated process, we studied the effect of pyridoxal 5'-phosphate on the synthesis of renal 24-hydroxylase in rats. When pyridoxal 5'-phosphate was infused to rats, renal 24-hydroxylase activity was suppressed, consequently, degradation of calcitriol was also reduced in these animals. Thus, chemicals capable of Schiff base formation potentially could alter the physiological function of VDR and calcitriol.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗