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Biomedical subjects

F Y Huang

Publications and source records attributed to F Y Huang.

At least 73 records · Page 4Linked to original sources
PubMed1993

Differences in temperature changes between pediatric and adult patients after cardiopulmonary bypass.

Nasopharyngeal (NPT) and rectal (RT) temperatures were continuously monitored in 51 adult or pediatric patients undergoing cardiac surgical procedures until 1 hour after the termination of cardiopulmonary bypass (CPB). The measurement also included the lowest NPT achieved and the dwelling time at that temperature on CPB, the rewarming time, the time on CPB, and the time that the chest remained opened after CPB. After the termination of CPB, the decrease of NPT (afterdrop) was significantly greater in the adult group than in the pediatric group. The mean decrease in adult patients was 1.34 +/- 0.65 degrees C versus 0.63 +/- 0.8 degrees C in pediatric patients. The combination of the NPT at the end of bypass (EndNPT), body weight times the EndNPT, and the dwelling of the lowest temperature times the EndNPT could predict 45% of the afterdrop. It is concluded that afterdrop occurs to a lesser degree in pediatric patients than in adults. This may be due to more efficient supplying of external heat to pediatric patients in whom there is a larger body surface area to weight ratio.

Adult↗
PubMed1993

The effect of hydration on the dynamics of trimethoprim bound to dihydrofolate reductase. A deuterium NMR study.

To determine the effect of hydration on the dynamics of a protein complex, we used deuterium nuclear magnetic resonance (NMR) techniques to examine a trimethoprim (TMP)/E. coli dihydrofolate reductase (DHFR) complex in its lyophilized, partially hydrated, polycrystalline, and ammonium sulfate-precipitated states. The results indicate that TMP is rigid in the lyophilized powder state. The dynamic behavior could be restored by partial rehydration. At 30 wt% hydration the deuterium spectrum of the partially hydrated sample was indistinguishable from that of the polycrystalline and ammonium sulfate-precipitated samples, suggesting that the structure of the protein/TMP complex is similar in the three physical states. Furthermore, we found that the para- and meta-methoxyl groups have very different dynamical behavior.

Biophysical Phenomena↗
PubMed1993

Duplex Doppler assessment of visceral and cerebral blood flow velocity in full-term newborns.

To assess postnatal visceral and cerebral blood flow velocity changes, transcutaneous duplex Doppler ultrasound was used to measure the superior mesenteric artery (SMA), celiac artery (CA) and anterior cerebral artery (ACA) blood flow velocity in 20 normal healthy newborns. Doppler indices of peak systolic velocity (PSV), time-averaged mean velocity, end-diastolic velocity and Pourcelot resistance index (PI) were measured immediately after delivery and consecutively for three days at 24-hour intervals. At 24 hours after delivery, PSV had risen significantly in the CA, SMA and ACA (p < 0.01). The PI had decreased significantly in all three vessels. We conclude that the most prominent hemodynamic changes in the splanchnic and cerebral artery circulation occur within 24 hours after delivery in normal healthy newborns. Possible mechanisms are discussed.

Blood Flow Velocity↗
PubMed1993

[Midazolam and Meperidine for colonoscopy].

We studied the sedative, analgesic and amnesic effects of intravenous midazolam and meperidine for colonoscopy, and also compared patient's satisfaction, changes of vital signs, safety and complications with intramuscular meperidine during the colonoscopy. Two hundred and ninety-nine patients undergoing physical check-up were randomized to receive intramuscular meperidine 50 mg and Hyoscine-N-Butylbromide (buscopan) 20 mg (Group IM-MB, n = 57) or intravenous midazolam 0.05 mg/kg, meperidine 1 mg/kg and buscopan 20 mg (Group IV-MMB, n = 242) before colonoscopy. All patients were closely observed and arterial oxygen saturations (SaO2) were monitored with pulse oximeter in Group IV-MMB. The demographic data of both groups were similar. There were significantly more severe pain responses (grimacing, moaning, shouting for pain, abdominal rigidity and body moving during colonoscopy) in Group IM-MB (51%) than in Group IV-MMB (13%) (p < 0.01). In immediate procedure recall after recovery from medications, 39% of Group IM-MB remembered severe pain during colonoscopy and only 3% of Group IV-MMB did (p < 0.01). 92% of Group IV-MMB who felt satisfactory with the medications were significantly higher than 21% in Group IM-MB (p < 0.01). Both groups significantly increased in heart rate after the injection of medications (p < 0.01). Group IM-MB increased 15 +/- 18% and Group IV-MMB 61 +/- 28% with significant difference between groups (p < 0.01). This might be caused by meperidine, buscopan, and relative hypovolemia of patients. There were significant decreases in SaO2 in Group IV-MMB, mean 4.5 +/- 1.7% (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Release of immunoreactive [Met5]enkephalin and cholecystokinin from the spinal cord by beta-endorphin administered intraventricularly in the pentobarbital-anesthetized rat.

Beta-endorphin (4 micrograms) injected i.v.t. induced the release of immunoreactive [Met5]enkephalin and sulfated cholecystokinin octapeptide (CCK-8s) from the spinal cord in the pentobarbital-anesthetized rat. The inhibition of the tail-flick response induced by beta-endorphin given i.v.t. was antagonized by i.t. injection of CCK-8s and potentiated by i.t. administration of the antibody to CCK-8s. The findings give support to the hypothesis that endogenous CCK-8s in the spinal cord may play a negative feedback role in modulating beta-endorphin-induced antinociception.

Anesthesia↗
PubMed1992

Meconium ileus-like condition in Chinese neonates.

Between January 1985 and May 1990, 16 neonates were treated for meconium ileus (MI) at this hospital. All babies were born to Chinese couples. Seven of them were premature, but none of them weighed less than 1,000 g. Eight patients underwent operations either because of mistaken diagnosis, as ileal atresia or long-segment Hirschsprung's disease, or because of complicated MI, including two meconium peritonitis and one associated with ileal atresia. Gastrograffin enema was successful in management of eight uncomplicated MI. The albumin content in the meconium of the last nine cases, including four complicated cases, ranged from 9.2 to 93.3 mg/g dry meconium. Usually, albumin is not present in normal meconium. All cases received sweat test, which were negative. Three patients died in the follow-up period. Sepsis of unknown origin, multiple congenital anomalies, and severe metabolic problems were the causes of death. The other 13 patients are doing well. They have exhibited no pulmonary or digestive problems during their follow-up period, which ranged from 11 months to 5 years. They are healthy and receive regular diets. Growth and development are appropriate for their age groups.

Albumins↗
PubMed1992

T lymphocyte changes in open heart surgery.

To investigate the effect of open heart surgery on T lymphocytes and their subpopulations, 20 patients, who had undergone moderate- to high-dose fentanyl anesthesia and a cardiopulmonary bypass (CPB), were studied using flow cytometry techniques and monoclonal antibodies during and after surgery. The ages of these patients ranged from four to 61 years with eight being male and 12 being female. The disease entity consisted of four with coronary, six with congenital and 10 with valvular heart disease. No cyanotic patients were included in this study. Peripheral blood samples were collected before anesthesia, immediately before the surgical incision, on the first postoperative day (POD1) and on the second postoperative day (POD2), respectively. We found no significant changes in the percentage of total T cells (T3), or helper (T4) and suppressor (T8) T cells during anesthesia before the surgical incision. On POD1, all T lymphocyte subset percentages decreased significantly when compared to pre-operative values (total T cells: 58.4 +/- 12.6 vs 24.4 +/- 8.4, helper T cells: 33.3 +/- 10.1 vs 15.4 +/- 6.3, suppressor T cells: 23.0 +/- 6.4 vs 10.0 +/- 4, all p less than 0.001) but returned to preoperative levels on POD2. Throughout the study period, there were no significant changes in the T helper cell to T suppressor cell ratio. In spite of the transient decrease in T lymphocytes and their subpopulations, no clinical evidence of infection was noted in any patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Can cancer pain attenuate the physical dependence on chronic long-term morphine treatment?

This prospective and comparative study was designed to determine the role of cancer pain and attitudes towards morphine in attenuating the intensity and duration of physical dependence following chronic morphine treatment. Morphine was administered via a stepwise ladder approach in order of oral, spinal and intravenous routes depending on the adequacy of analgesia. On-demand titration of a dose, either upward or downward, was liberal and unlimited. Withdrawal strategy was evaluated and initiated either by patients (PI group) or their families (FI group). The manifestation of physical dependence on morphine was compared between patients who successfully withdrew (total withdrawal), and patients who failed to withdraw (episodic withdrawal), from morphine for a period of more than two weeks. Eighty-eight out of 627 patients (14.1%) were excluded from our protocol; 75% of these exclusions were due to objections toward morphine as the major form of analgesic. Drop-out due to poorly tolerated side effects was relatively rare (18.2%). Fifty-four (10.0%) achieved total withdrawal and 212 (39.3%) experienced episodic withdrawal. Non-pain-related abstinence symptoms were highly prevalent but were tolerable for both groups. Pain-related symptoms were more exaggerated during episodic withdrawal. Intolerable pain, rather than physical dependence, contributed to the failure to withdraw from morphine. Among a total of 539, addiction was found in only one patient (0.18%) who began drug use long before entering our protocol. Attitudes towards morphine affect the acceptance of treatment and hasten the withdrawal strategy. Families were more anxious about morphine than the patients themselves which led to more aggressive, but less tolerable, withdrawal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Patient-controlled intravenous versus epidural analgesia after major joint replacement].

The analgesic efficacy, side effects, and satisfaction of patient-controlled analgesia (PCA) with intravenous and epidural morphine for postoperative pain were evaluated in this study. Twenty patients undergoing major joint replacement surgery were randomly allocated to intravenous PCA (IPCA) group or epidural PCA (EPCA) group. All patients had a standardized balanced anesthesia, and an epidural catheter was introduced after the operation in EPCA group. Postoperative pain relief was evaluated with verbal pain scale. The result showed that pain intensity and pain relief were similar in either group without significant difference (p greater than 0.05). Morphine consumption in IPCA group was 1.72 +/- 0.30 mg/h in the postoperative 0 - 12 h and 1.14 +/- 0.44 mg/h in 12 - 24 h. In EPCA group, relatively low doses of morphine were used, i.e., 0.20 +/- 0.07 mg/h in the postoperative 0 - 12 h and 0.17 +/- 0.07 mg/h in 12 - 24 h. Both groups showed an "incomplete" but satisfactory analgesia with relatively low doses of morphine. The "equianalgesic dose ratio" of IPCA to EPCA with morphine was approximately 8.5:1. Sedation was minimal in both groups. No respiratory depression developed in all patients. Nausea and vomiting were the most prominent side effects which might limit the usefulness of PCA. The incidence was 5 out of 10 patients in IPCA group and 4 out of 10 patients in EPCA group, despite under the treatment of droperidol (15 micrograms/kg, iv, prn) for most of the patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The effect of total intravenous propofol on spontaneous respiration during anesthesia for minor surgery.

To evaluate adequate anesthetic depth without unacceptable respiratory consequences during total propofol intravascular anesthesia without intubation, the respiratory response was studied in 20 healthy patients (ASA class I or II), aged 20-50, premedicated with fentanyl 2 micrograms/kg. Anesthesia was induced in all patients with propofol 2.5 mg/kg, subsequently maintained by continuous propofol infusion at 12 mg/kg/h. An additional bolus of 20-60 mg propofol was given when anesthesia was considered inadequately. Assisted ventilation with 100% oxygen through a face mask was applied when apnea time was longer than 60 s. The mask was removed when patients regained spontaneous breathing. During induction stage, 7 patients developed apnea which required ventilatory support, although the period of apnea was short. Among them four regained spontaneous breathing within 5 min, and three within 10 min. PaCO2 significantly increased at both 10 min and 20 min after induction as compared with those before induction (p less than 0.05), while the change between 10 min and 20 min after induction was not statistically different. PaO2 showed little change and also it was not statistically significant. During maintenance of anesthesia spontaneous ventilation was stable and adequate. Though mild hypercapnia was noted, no medication was necessary. There was no episode of arterial oxygen desaturation throughout the course of maintenance. All patients could be adequately anesthetized except for six patients who required additional dose for insufficient anesthetic depth. No major adverse reactions occurred during or after induction. We concluded that the respiratory effect of propofol in total intravenous anesthesia could be divided into two stages: the induction stage and the maintenance stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

15N NMR studies of the conformation of E. coli dihydrofolate reductase in complex with folate or methotrexate.

We have employed 15N NMR to characterize the conformations of Escherichia coli dihydrofolate reductase (ECDHFR) in complex with [5-15N]folate or [5-15N]methotrexate (MTX). Two 15N resonances were observed for DHFR/MTX binary complex. The relative population of these two conformations is pH dependent. Addition of NADP+ or NADPH results in the disappearance of the low field resonance. In contrast, only one conformation was observed for both the DHFR/folate and DHFR/folate/NADP+ complexes. However, the 15N chemical shift of [5-15N]folate in the binary DHFR/folate complex is 7.28 ppm upfield from that of the ternary complex, suggesting the possible loss of a hydrogen bonding to N5 of folate in the ternary complex.

Escherichia coli↗
PubMed1991

The conformations of trimethoprim/E. coli dihydrofolate reductase complexes. A 15N and 31P NMR study.

We have employed 15N and 31P NMR techniques to characterize the conformations of trimethoprim (TMP)/E. coli dihydrofolate reductase (DHFR) complexes in the presence and absence of NADPH and NADP+. A single conformation was observed for TMP/DHFR, NADP+/DHFR, NADPH/DHFR, and TMP/NADPH/DHFR complexes. In the ternary complex of TMP/NADP+/DHFR both the 15N and 31P spectra revealed the presence of two conformations. However, the conformations of TMP and NADP+ in the ternary complex may not be correlated, resulting in the possible existence of four conformations for the protein ternary complex.

Escherichia coli↗
PubMed1991

Annual average radon concentrations in California residences.

A study was conducted to determine the annual average radon concentrations in California residences, to determine the approximate fraction of the California population regularly exposed to radon concentrations of 4 pCi/l or greater, and to the extent possible, to identify regions of differing risk for high radon concentrations within the state. Annual average indoor radon concentrations were measured with passive (alpha track) samplers sent by mail and deployed by home occupants, who also completed questionnaires on building and occupant characteristics. For the 310 residences surveyed, concentrations ranged from 0.10 to 16 pCi/l, with a geometric mean of whole-house (bedroom and living room) average concentrations of 0.85 pCi/l and a geometric standard deviation of 1.91. A total of 88,000 California residences (0.8 percent) were estimated to have radon concentrations exceeding 4 pCi/l. When the state was divided into six zones based on geology, significant differences in geometric mean radon concentrations were found between several of the zones. Zones with high geometric means were the Sierra Nevada mountains, the valleys east of the Sierra Nevada, the central valley (especially the southern portion), and Ventura and Santa Barbara Counties. Zones with low geometric means included most coastal counties and the portion of the state from Los Angeles and San Bernardino Counties south.

Air Pollution, Indoor↗
PubMed1991

Irritant effects of formaldehyde exposure in mobile homes.

This paper reports the irritant effects associated with formaldehyde exposures in mobile homes. Week-long, integrated formaldehyde concentrations were measured using passive monitors in summer and winter while the mobile home residents continued their normal activities. Information on acute health problems, chronic respiratory/allergic illnesses, smoking behavior, demographic variables, and time spent at home was obtained on over 1000 individuals during the sampling period. Measured formaldehyde concentrations varied from under the limit of detection (0.01 ppm) to 0.46 ppm. Formaldehyde exposure was estimated for each individual by multiplying the concentration measured in his or her home by the time he or she spent at home. Irritant effects were found to be associated with formaldehyde exposure after controlling for age, sex, smoking status, and chronic illnesses using a logistic procedure. Some of the interaction terms found to be significant indicated that there were synergistic effects between formaldehyde exposure and chronic health problems.

Adolescent↗