Loss of visibility of the neurohypophysis as a sign of central diabetes insipidus.
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Child, Preschool↗
Biomedical subjects
F Y Huang
Publications and source records attributed to F Y Huang.
Dynamics of trimethoprim bound to dihydrofolate reductase--a deuterium NMR study.
We have employed deuterium NMR techniques to determine the dynamics of trimethoprim (TMP) in a binary complex with dihydrofolate reductase (DHFR) or in a ternary complex with DHFR and cofactor NADP+ in the fully hydrated state. TMP was deuterated at the following positions: (2',6'-D2)TMP, (3'-Ome-D3)TMP and (3',4'-Ome-D6)TMP. Dynamics of TMP were deduced from lineshape simulation and relaxation measurements of the deuterium NMR powder spectra of the three samples obtained at various temperatures. The results showed that in the polycrystalline state the TMP molecule is very rigid. The only detectable motion is the methyl group rotation at a rate of 10(10) s-1 at 25 degrees C, as determined from simulation of the partially relaxed powder patterns. When bound to DHFR a residual deuterium quadrupole splitting of 140 kHz was observed for (2',6'-D2)TMP at temperatures up to 30 degrees C, suggesting that the benzyl ring in the bound state is also very rigid. In contrast, in the binary complex with DHFR the methoxyl groups of TMP undergo librational motion of 10(7) s-1 about the C3-O bond at an amplitude of 54 degrees for the meta methoxyl group and about the C4-O bond at an amplitude of 70 degrees and similar rate for the para methoxyl group at 30 degrees C. The presence of the cofactor, NADP+, appears to tighten up the binding pocket such that the motion freedom of TMP is more restricted. The rigidity of TMP in a protein complex as revealed by our deuterium NMR results is in accord with the tight binding of TMP to DHFR.
Deuterium↗
Improvement of arterial oxygenation by selective infusion of prostaglandin E1 to ventilated lung during one-lung ventilation.
BACKGROUND: One-lung anesthesia provides a better surgical field for thoracic procedures but also impairs the arterial oxygenation and venous admixture. During one-lung ventilation, pulmonary vasoconstriction is assumed to be present within both ventilated and collapsed lungs. We propose that arterial oxygenation could be optimized by offsetting the vasoconstriction within the microcirculation of ventilated lung. METHOD: In an anesthetized dog model, incremental doses of prostaglandin E1 (PGE1) were selectively infused into the main trunk of the pulmonary artery of the ventilated lung after one-lung ventilation for 60 min (PGE1 group, n = 9). Arterial oxygenation and calculated venous admixture (Qs/Qt) was also assessed in a time-course control group (Control group, n = 5). During two-lung ventilation (FIO2: 0.66), arterial PO2 and venous admixture was 44.2 +/- 3.5 kPa and 10.7 +/- 2.3%, respectively. One-lung ventilation (FIO2: 0.66) with left lung collapsed reduced arterial PO2 to 11.6 +/- 1.7 kPa and increased venous admixture to 40.7 +/- 5.8% (P<0.001). Venous O2 tension also decreased from 6.3 +/- 0.7 kPa to 5.0 +/- 0.6 kPa with a slight increase in mean pulmonary artery pressure and pulmonary vascular resistance (P<0.05). RESULTS: During selective infusion of PGE1 at a dose of 0.04 to 0.2 mu g kg-1 min-1, there was a dose-dependent improvement in arterial PO2 with a parallel reduction of venous admixture during one-lung ventilation. Arterial PO2 increased to a maximum of 23.0 +/- 4.3 kPa, and the venous admixture decreased significantly to a minimum of 27.4 +/- 4.2% by PGE1 at a dose of 0.04-0.4 mu g kg-1 min-1 (P<0.01). PGE1 resulted in a small increase in cardiac output and decreases of pulmonary pressure and pulmonary vascular resistance at a relatively high dose of 0.4 mu g kg-1 min-1 during selective infusion (P<0.05). CONCLUSIONS: These results suggest that a selective pulmonary artery infusion of PGE1 to the ventilated lung within the dose range of 0.04-0.4 mu g kg-1 min-1 is practical and effective to improve arterial oxygenation and reduce venous admixture during one-lung ventilation.
Alprostadil↗
Case report: agenesis of the right lung diagnosed by three-dimensional reconstruction of helical chest CT.
Unilateral pulmonary agenesis is extremely rare and the diagnosis can be made by a number of conventional methods. We report two cases: a 16-day-old girl and a 14-year-old girl presenting with tachypnoea in whom three-dimensional reconstruction of helical chest computed tomography was used to demonstrate the complete absence of the carina, right main bronchus and right lung. To our knowledge, these are the first cases of right lung agenesis diagnosed by this method.
Adolescent↗
Loss of visibility of the neurohypophysis as a sign of central diabetes insipidus.
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Child, Preschool↗
Resolution of vesicoureteral reflux during medical management in children.
A retrospective study was performed to evaluate the results of medical management of primary vesicoureteral reflux (VUR) in infants and children. The charts of 105 patients (74 boys, 31 girls) with 167 refluxing ureters were reviewed. The age at diagnosis ranged from 3 days to 9.2 years (mean 1.3 +/- 1.9 years). The mean duration of follow-up was 2.4 +/- 1.5 years. We found that the patient's sex did not influence the fate of VUR and its complications. Patients whose reflux improved while being managed medically were younger than those who did not improve, and the younger the patient the sooner the reflux resolved. Improvement and resolution of reflux were also related to grade, and the lower the initial grading the sooner the reflux resolved. Spontaneous resolution rates of reflux were 92.3%, 76.2%, 61.7%, and 32.0% for grades I, II, III, and IV, respectively. No ureters with grade V reflux resolved without complications. The most common complications in our series were renal scarring and secondary obstructive uropathy.
Age of Onset↗
Limb defects after chorionic villus sampling.
OBJECTIVE: To clarify the association between limb defects and chorionic villus sampling (CVS). METHODS: Questionnaires were sent to 165 major obstetric units in Taiwan to survey the incidence of limb defects with and without CVS exposure during 1991. Limb defects with CVS exposure from September 1990 to June 1992 were also surveyed. The spectrum of limb defects in CVS-exposed and general populations were compared by the Poisson test. RESULTS: The incidence of limb defects in the surveyed general population in 1991 was 0.032% and that with CVS exposure was 0.294%, a statistically significant difference (P < .001). The incidence of severe limb defects in the general population was 0.0026% and that with CVS exposure was 0.22%, also statistically significant (P < .001). Twenty-nine cases of limb defects after CVS were reported from September 1990 until June 1992: 19 cases with transverse limb reduction, two with mid-palm reduction, seven with adactyly or hypodactyly, and one with syndactyly. Four cases also had oromandibular-limb hypogenesis syndrome. CONCLUSIONS: The incidence of limb defects, especially the severe types, was increased after CVS. The spectrum of limb defects with CVS exposure was more severe than the limb defects seen in the general population and showed a specific pattern ranging from hypodactyly, adactyly, and transverse limb reduction, to oromandibular-limb hypogenesis. A correlation between the severity of limb defects and the timing of CVS was suggested.
Abnormalities, Multiple↗
Skipping of exon 12 as a consequence of a point mutation (1898 + 5G-->T) in the cystic fibrosis transmembrane conductance regulator gene found in a consanguineous Chinese family.
A point mutation (1898 + 5G-->T) located five base pairs downstream from the donor splice site in intron 12 of the CFTR gene has been identified in a consanguineous CF patient of Chinese origin. To determine if this nucleotide substitution could affect mRNA splicing, PCR analysis was performed with RNA isolated from the lymphoblastoid cell line of the mother of the deceased patient. While exon 12-minus transcript was detected in this sample, it was also found in individuals without 1898 + 5G-->T, albeit in a smaller proportion. Using a sequence polymorphism associated with each of the two alleles in the mother, however, we showed that mutant transcript was almost exclusively produced by the 1898 + 5G-->T allele. Skipping of exon 12 would result in the deletion of 29 amino acids from the first nucleotide binding domain of CFTR, rendering the protein non-functional. The possibility of a low level (< or = 2.5%) of normal transcript from the mutant allele cannot be excluded and it may explain the pancreatic sufficient phenotype of the patient. The 1898 + 5G-->T mutation was found in two other CF patients of Chinese origin, but it was not detected in 192 CF chromosomes of Caucasian origin and 30 other chromosomes from Chinese individuals without a family history of CF.
Base Sequence↗
Neonatal-onset chronic intestinal pseudo-obstruction syndrome.
Between January 1985 and January 1990, six cases of neonatal-onset chronic intestinal pseudo-obstruction syndrome (CIPS) were identified. Failure to gain weight in six cases, abdominal distention in five, and vomiting in five were the most common presenting symptoms. The contrast studies of the gastrointestinal tract demonstrated delayed transit time in 6/6, jejunal or ileal dilatation in 1/6, megaduodenum in 1/6, dilatation of the colon with barium retention in 4/6, and microcolon in 1/6. Urinary tract involvement was noted in three patients. Laparotomy, performed in three patients, revealed no mechanical obstruction. Except for hypoganglionosis in Patient 4, no recognizable neuropathy or myopathy was noted histopathologically. Four patients expired within 2 months after discharge. We conclude that CIPS with neonatal onset should be suspected when infants have urinary retention and abdominal distention or constipation beginning at birth or soon after. The prognosis of CIPS presenting in the newborn period appears worse than that presenting in childhood or adulthood.
Abdomen↗
A clinicopathological study of idiopathic nephrotic syndrome in children.
This paper retrospectively examines the association of outcome with histological and clinical manifestations in 107 pediatric patients with idiopathic nephrotic syndrome (INS). At the time of renal biopsy, the patients were between 2 and 15 years of age. The interval from the onset of the disease to renal biopsy ranged from 1 to 156 months with a mean of 21 months. Continuous clinical follow-up was successfully conducted in 96 patients. The average duration of INS in these patients was 86.6 months (31 to 208 months). IgM deposition in the mesangium may play an important role in the pathogenesis of INS and our data showed that even in a minor glomerular abnormality (MCNS) subgroup, nearly half of the cases (42.9%) showed mesangial IgM deposition. However, the severity of hematuria, response to drug therapy with either steroids or cyclophosphamide, and the outcome, were not related to the presence or absence of IgM deposition, but were more closely associated with the type of histological category. The subgroup of patients with focal segmental glomerulosclerosis (FSGS) and diffuse mesangial proliferation (FSGS + DP) showed the most significant ultrastructural changes with positive mesangial IgM deposition (73.6%). The presence of IgM deposition in most of the patients in the subgroups with diffuse mesangial proliferative glomerulonephritis (DPGN) and FSGS + DP closely corresponded to the presence of electron-dense mesangial deposition. The FSGS + DP subgroup had a high incidence of denudation, vacuolization and detachment of podocytes, partial collapse of the glomerular basement membrane, and a very high incidence of resistance to steroid therapy.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Histomorphometric study in children with idiopathic nephrotic syndrome.
From 1981 to 1987, renal specimens obtained from 91 children with idiopathic nephrotic syndrome were categorized into 5 histologic subgroups, according to the WHO classification. We analyzed differences in the ratios of the size of the mesangial stalks and attached capillary, including the Bowman's space between the capillary tufts (E), mesangial matrix (Mx), and approximate capillary lumens (E-Mx) to the whole glomerular area of these subgroups using the histomorphometer-IBAS. Focal segmental glomerulosclerosis with diffuse mesangial proliferation (FSGS + DP) had the largest matrix area (Mx/G > 0.5), and smallest capillary lumen size (E/G-Mx/G) (0.3474 +/- 0.0702). On the contrary, FSGS with minimal change (FSGS + MC) had the smallest mesangial matrix (Mx/G), 0.2834 +/- 0.07726, but preserved a larger capillary lumen (0.427 +/- 0.1215). The approximate size of capillary lumens, from the smallest to the largest, was in the following order: FSGS + DP, diffuse mesangial proliferative glomerulonephritis (DPGN), focal segmental proliferative glomerulonephritis (FSPGN), FSGS + MC and minimal change nephrotic syndrome (MCNS). The ratio of the total number of mesangial cells to the area of the whole glomerulus (MCN/G) derived from the light microscopic examination was parallel to the value of Mx/G obtained by the histomorphometric technique. In summary, we introduced the histomorphometric technique using the histomorphometer-IBAS for quantitative measurement of various areas in the glomeruli. The data derived from the system is compatible with those obtained by experienced nephrologists, suggesting that the histomorphometric technique is helpful in histopathology. It is hoped that this new methodology will be used more extensively in the near future.
Adolescent↗
Physician aid in dying and the relief of patients' suffering: physicians' attitudes regarding patients' suffering and end-of-life decisions.
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Attitude of Health Personnel↗
Time of the first defaecation and urination in very low birth weight infants.
The time for passage of the first stool and urine was studied in 111 infants who weighed less than 1500 g at birth. Delayed passage of the first stool (greater than 24 h) was noted in 25 (22.5%) infants of this group, including 7 cases (6.3%) in whom the delay was greater than 48 h (4 on the 3rd day, 2 on the 4th day, 1 on the 6th day of life, respectively). Three (2.7%) cases had delayed passage of the first urine (at 25, 25, and 45 h of life, respectively). Significant differences between the two groups with delayed and nondelayed passage of the first stool were noted in both the gestational age and in the time of the first enteral feeding. In very low birth weight infants, delay in the passage of the first stool is a common occurrence. This delay is probably due to physiological immaturity of the motor mechanisms of the gut, and lack of triggering effect of enteral feeds on gut hormones. As far as passage of the first urine was concerned, there were no significant perinatal factors found between the delayed and nondelayed groups.
Defecation↗
Acute segmental obstructing enteritis in children.
We studied a group of 15 children with acute segmental enteritis associated with intestinal obstruction. The disease is characterized by fever, leukocytosis, copious bilious vomiting, and severe abdominal pain with signs of intestinal obstruction. Exploration revealed varying degrees of segmental ischemic change in the small bowel, but surgery seemed to be unnecessary in most cases. Antibiotics were effective in nonoperative cases. The clinical illness lasted 10-14 days. The disease was self-limited, and no mortality was found in our series. To our knowledge, this is the first report of this disease entity in Chinese children.
Abdominal Pain↗
Duplex ultrasonographic assessment of gut blood flow velocity: effect of meal composition in normal full-term newborns after first feed.
We used transcutaneous duplex Doppler ultrasound to measure superior mesenteric artery and celiac artery blood flow velocity in 45 normal healthy newborn infants. Doppler indices of PSV, TAMV, EDV, and PI were measured immediately before and after feeding at 15 minute intervals up to 75 minutes. Maximal changes were compared with preprandial baseline values. There were no significant differences between the preprandial and postprandial blood pressures and heart rates. In the superior mesenteric artery the PSV, TAMV, and EDV rose progressively and peaked 30 minutes after feeding in both the milk-fed group and the 5% glucose, water-fed group over baseline (73 versus 41% and 110 versus 63%, 130 versus 100%) (P < 0.05). The PI decreased significantly in the milk-fed group only. There were no significant changes in any blood flow velocity parameters derived from the celiac artery. We conclude that duplex ultrasonography provides a noninvasive means of studying the reactivity of the splanchnic arterial circulation to different stimuli. The chemical composition of the meal is a significant factor determining postprandial mesenteric hyperemia.
Blood Flow Velocity↗
Congenital biliary tract dilatation in infancy and childhood--74 cases experience.
This report presented a twelve-year experience from 1981 to 1992. Seventy-four cases of congenital biliary tract dilatation were at diagnosed an age of 6 days to 16 years. Twenty-two cases were infants. There were 54 females and 20 males. The ratio of female to male was 2.7:1. The classic triad of abdominal pain, jaundice and a palpable mass was seen in eleven cases (14.9%). Most children suffered from abdominal pain (50/74), vomiting (45/74), anorexia (42/74) and jaundice (34/74). Prolonged jaundice was the main symptom in infancy (15/22). A long common pancreatico-biliary channel was seen in six cases (6/47); the bile amylase level was elevated in five cases (5/20), one patient had a complex union with obstructive jaundice. All these cases were diagnosed by preoperative sonography accurately (100%). According to the Todani's classification, type Ia was the most common (40/74), followed by type IV-A (25/74) and type Ic (8/74). Cholelithiasis (13/74), perforation (9/74), and atresia/stenosis of distal choledochus (8/74) were the most common associated conditions. Cyst excision with biliary tract reconstruction was performed in all cases. Reoperation was needed in ten cases. Two cases died postoperatively due to sepsis and cholangitis induced hepatic failure.
Adolescent↗
Cerebral hemorrhage following spinal anesthesia for cesarean section: a case report.
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Adult↗
Titration of histidine 62 in R67 dihydrofolate reductase is linked to a tetramer<-->two-dimer equilibrium.
R67 dihydrofolate reductase (DHFR) is an R-plasmid encoded protein that confers clinical resistance to the antibacterial drug trimethoprim. To determine whether an acidic titration in kinetic pH profiles is related to titration of histidines 62, 162, 262, and 362, the stability of tetrameric R67 DHFR has been monitored as a function of pH. For the pH range 5-8, tetrameric R67 DHFR reversibly dissociates into dimers, as monitored by ultracentrifugation and molecular sieving techniques. From the crystal structures of dimeric and tetrameric R67 DHFR [Matthews et al. (1986) Biochemistry 25, 4194-4204] (Narayana, Matthews, and Xuong, personal communication), symmetry-related histidines 62, 162, 262, and 362 occur at the two dimer-dimer interfaces and protonation of these residues could destabilize tetrameric R67 DHFR. Ionization of these histidines was confirmed by monitoring the chemical shifts of the C2 proton in NMR experiments, and best fits of an incomplete titration curve yield a pKa of 6.77. Since tryptophans 38, 138, 238, and 338 also occur at the dimer-dimer interfaces, fluorescence additionally monitors the tetramer-two dimers equilibrium. When fluorescence was monitored over the pH range 5-8, a protein concentration dependence of fluorescence was observed and global fitting of three titration curves yielded Kd = 9.72 nM and pKa = 6.84 for the linked reactions: [formula: see text] Modification of H62, H162, H262, and H362 by diethyl pyrocarbonate stabilizes dimeric R67 DHFR and causes a 200-600-fold decrease in catalytic efficiency. Decreased catalytic activity in dimeric R67 DHFR is presumably due to loss of the putative single active site pore found in tetrameric R67 DHFR.
Chromatography, Gel↗