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Biomedical subjects

L Chan

Publications and source records attributed to L Chan.

At least 541 records · Page 30Linked to original sources
PubMedDate not supplied

Backboard versus mattress splint immobilization: a comparison of symptoms generated.

The study objective was to compare spinal immobilization techniques to a vacuum mattress-splint (VMS) with respect to the incidence of symptoms generated by the immobilization process. We used a prospective, cross-over study in a university hospital setting. Participants consisted of 37 healthy volunteers without history of back pain or spinal disease. Interventions consisted of two phases. In Phase I, subjects were randomly assigned to be immobilized on either a wooden backboard or a mattress-splint for 30 min. The incidence and severity of any symptoms generated by the immobilization process were recorded. In Phase II, the two groups were again tested after a 2-week washout period, with the method of immobilization being reversed. Symptoms and severity were again recorded. Pain symptoms were confined to four anatomic sites: Occipital prominence, lumbosacral spine, scapulae, and cervical spine. After adjusting for the effect of order of exposure, subjects were 3.08 times more likely to have symptoms when immobilized on a backboard than when immobilized on the VMS. They were 7.88 times more likely to complain of occipital pain and 4.27 times more likely to complain of lumbosacral pain. Severity of occipital and lumbosacral pain was also significantly greater during backboard immobilization. We conclude that, when compared to a VMS, standard backboard immobilization appears to be associated with an increased incidence of symptoms in general and an increased incidence and severity of occipital and lumbosacral pain in particular.

Adolescent↗
PubMedDate not supplied

A critical evaluation of the putative role of C3adesArg (ASP) in lipid metabolism and hyperapobetalipoproteinemia.

The acylation stimulating protein, ASP is a small, basic serum protein capable of stimulating triglyceride synthesis in cultured fibroblasts and adipocytes. Sequence analysis of ASP has shown that ASP is identical to C3adesArg the inactive fragment of the complement anaphylatoxin peptide, C3a. It has been proposed that C3adesArg (ASP) can be generated by mature adipocytes secreting the three complement proteins: complement protein C3, factor B and factor D (adipsin). There have also been indications that adipocytes may express a specific C3adesArg (ASP)-receptor that is distinct from the recently cloned C3a-receptor. This suggests that C3adesArg (ASP) acts as an adipocyte autocrine and that it plays a central role in the metabolism of adipose tissue. Based on these observations a hypothesis for the etiology of hyperapobetalipoproteinemia (hyperapoB) has been proposed. Hyperapobetalipoproteinemia (hyperapoB), is a familial lipoprotein disorder characterized by increased hepatic secretion of very low density lipoprotein (VLDL) and low density lipoprotein (LDL) particles. If C3adesArg (ASP) function in the adipose tissue is impaired, a reduced rate of triglyceride synthesis will follow, generating an increased flux of fatty acids to the liver. In response to an increased flow of fatty acids, the liver will increase its production of VLDL particles yielding the phenotype of hyperapoB. This review critically assesses this hypothesis and the potential role of C3adesArg (ASP) as a major determinant for triglyceride synthesis in the light of data collected in vitro and in vivo.

Adipocytes↗
PubMedDate not supplied

Antenatal triiodothyronine improves neonatal pulmonary function in preterm lambs.

OBJECTIVE: To characterize 1) pulmonary gas exchange, 2) pulmonary function, 3) lung fluid and tissue phospholipid content, and 4) thyroid hormone in the premature lamb (0.85 of term) after intra-amniotic administration of 100 micrograms of triiodothyronine (T3) 2 weeks before delivery. METHODS: Nine fetal lambs were given 100 micrograms of intra-amniotic T3 under ultrasound guidance at 112 +/- 1 days' gestation and delivered at 126 +/- 1 days (term = 149 days). Five saline-injected animals served as controls. Arterial blood gases, pulmonary mechanics, and lung volumes were compared between groups for 1 hour after delivery. At delivery, tracheal fluid and blood was taken for T3, and thyroxine (T4) levels. Tracheal fluid and lung tissues were assayed for total phosphorus and disaturated phosphatidylcholine. RESULTS: Triiodothyronine-treated lambs had significantly higher mean arterial pH and lower PCO2 than controls (P < .05) with a trend toward higher mean PO2. The dynamic lung compliance was increased by 54% with a 40% proportional increase in tidal volume and minute ventilation in the T3-treated group (P < .05). Functional residual capacity increased 69% (P < .05) without a change in specific compliance. The tracheal fluid and pulmonary phospholipids and tracheal fluid and plasma T3 and T4 levels were not different between the two groups. CONCLUSION: A single 100 micrograms dose of antenatal T3 significantly improves neonatal gas exchange and lung compliance. The improvement in lung function was not accompanied by an increase in pulmonary surfactant production. It is inferred that T3 improved lung function via accelerated structural development of the lung with an alternative possible effect on parenchymal connective tissue matrix.

Amniotic Fluid↗
PubMedDate not supplied

Plasma exchange in the treatment of hemolytic disease of the newborn.

Plasma exchange has become a widely used therapeutic tool in the treatment of immune-mediated disease. This technique has been applied to the treatment of gravid women whose high antibody titers and past history of stillbirths indicate a significant possibility of fetal loss due to HDN. The procedure was effective in decreasing both antibody titer and the quantity of antibody in four of five patients. In one other case, the antibody titer rose toward the end of the pregnancy; however, the quantity of anti-D remained low. The IgG:IgM ratio and the subclass specificity of IgG did not significantly change with treatment. Hematologic monitoring also indicated no adverse effects, and three of the five women delivered viable fetuses. Two of the other women produced infants only moderately affected by HDN but stillborn within days of intrauterine transfusion. The results indicate that plasma exchange is a useful therapeutic consideration in the sensitized gravid women.

Amniocentesis↗
PubMedDate not supplied

Comparison of capillary and venous glucose measurements in healthy volunteers.

BACKGROUND: Out-of-hospital (OOH) emergency personnel measure serum glucose in order to determine the need for dextrose therapy. Most devices that measure serum glucose are designed to use capillary blood obtained from a finger puncture. However, OOH emergency personnel often use venous blood obtained during intravenous line (IV) placement to determine serum glucose. OBJECTIVE: To compare capillary and venous glucose measurements. METHODS: This prospective study used healthy, non-fasting volunteers. Simultaneous venous and capillary blood samples were obtained from each subject. Glucose levels were measured using a glucometer designed for capillary samples. The capillary and venous measurements were compared using a Pearson correlation coefficient. Power analysis revealed that the study had the ability to detect a difference of 15 mg/dL. RESULTS: Ninety-seven volunteers (56 males, 41 females) with a mean age of 37 +/- 11.9 years were enrolled. The mean capillary and venous glucose values were 104.5 +/- 20.7 mg/dL and 109.7 +/- 22.4 mg/dL, respectively. The Pearson correlation coefficient was 0.24. CONCLUSIONS: The correlation between venous and capillary blood glucose measurements is relatively poor in this group of healthy volunteers. Further research must be conducted on patients at risk for abnormal blood glucose.

Adult↗
PubMedDate not supplied

Design and SAR study of a novel class of nucleotide analogues as potent anti-HCMV agents.

We have developed a novel class of 2-phosphonate 1,3-dioxolane nucleotide analogues, from which the guanine derivative displayed weak anti-HCMV activity. Further SAR studies led to the identification of both cis and trans guanine derivatives of tetrahydrofuran analogues as potent anti-HCMV agents, both in vitro and in vivo, compared to ganciclovir and HPMPC.

Animals↗
PubMedDate not supplied

Serum transaminase elevations in infants with rotavirus gastroenteritis.

Over a 6-week period, 35 (41%) of 86 infants admitted with diarrhea and dehydration were found to have human rotavirus (HRV) gastroenteritis, using the Rotazyme (RTZ) test. Serum transaminase levels were measured on 44 infants on admission and 72 infants during the first 3 days of hospitalization. On admission, RTZ-positive (RTZ+) infants had higher mean and median alanine aminotransferase (ALT) levels [mean 87.5 U/L in RTZ+ vs. 50.0 U/L in RTZ-negative (RTZ-), p = 0.001; medium 60 U/L in RTZ+ vs. 41 U/L in RTZ- infants, p = 0.002], and higher mean and median aspartate aminotransferase (AST) levels (mean 64.3 U/L in RTZ+ vs. 44.0 U/L in RTZ- infants, p = 0.008; median 67.5 U/L vs. 42.0 U/L, respectively, p = less than 0.05). On admission, 72% of RTZ+ vs. 19% of RTZ- infants had ALT levels greater than 50 U/L (p = 0.0004). Maximum ALT levels from the first 3 days were also higher in the RTZ+ group (67.7% of RTZ+ vs. 34.1% of RTZ- having levels greater than 50 U/L, p = 0.005). Transaminase elevations did not correlate with dehydration of any electrolyte abnormalities. These findings suggest that transaminase elevations are common in infants hospitalized with HRV enteritis.

Alanine Transaminase↗
PubMedDate not supplied

Magnetic resonance study of renal transplantation.

In the last few years, we have focused our research effort on the magnetic resonance spectroscopic (NMR) studies of organ transplantation in the rat. P-31 NMR was employed to study changes in high-energy phosphates, intracellular pH in vivo of transplanted kidneys either during normal function, while undergoing the rejection process or subjected to other insults (e.g. ischemia, cyclosporine nephrotoxicity, urinary obstruction) which may also cause graft dysfunction. Nuclear magnetic resonance (NMR) parameters, specifically relative peak areas and intracellular pH, accurately distinguished among the different causes of graft dysfunction. Ureteral obstruction was clearly identified by elevations in the phosphodiester/urine phosphate peak. Ischemia and rejection were both associated with increases in inorganic phosphates and phosphomonesters and decreases in the beta-phosphate peak of adenosine triphosphate but were distinguishable from each other by differences in intracellular pH which was normal in rejected allografts (7.33 +/- 0.07, n = 3) and low in ischemic allografts (7.00 +/- 0.05, n = 3, p less than 0.05). Grafts insulted with cyclosporine toxicity were not distinguishable from normal allografts by any of the parameters studied. To determine the temporal relationship of NMR changes in allograft rejection, similar studies were performed serially in a group of rejecting (R) kidneys (n = 7) and compared with a control group of nonrejecting (NR) kidneys (n = 7). Major decrease in adenosine triphosphate (ATP) with increases in Pi and a marked increase in the Pi/ATP ratio were noted in the R allografts over time. The R allografts could be completely segregated from the NR allografts on the basis of the Pi/ATP ratio by day 7. These data suggest that 31P NMR spectroscopy may have potential clinical application in differentiating among the causes of graft failure of human renal allografts.

Adenosine Triphosphate↗
PubMedDate not supplied

Early metabolic effects of hypotension on rat kidney.

Saturation-transfer phosphorus nuclear magnetic resonance (STNMR) has been applied to the rat kidney in vivo. The rate of renal metabolism determined by this method compares favorably with the renal oxygen consumption, assuming an ATP:oxygen ratio of 2. Hemorrhagic hypotension resulted in a 20% fall in renal blood flow and a significant fall in oxygen consumption. The rate of renal metabolism fell by 50%. This rate of ATP synthesis was below that required to maintain a normal [ATP], but renal [Pi] was not increased. When renal perfusion was reduced by 60%, intrarenal [Pi] rose. When [P1] was elevated, the method os STNMR no longer gave a reliable measure of the rate ATP synthesis, indicating that this new Pi pool was not in rapid chemical exchange with ATP. STNMR represents a useful noninvasive means of monitoring renal metabolic rate, with limitations due to insensitivity and the existence of multiple pools of intrarenal Pi.

Adenosine Diphosphate↗
PubMedDate not supplied

First-trimester needle embryofetoscopy and prenatal diagnosis.

OBJECTIVE: To demonstrate the efficacy of first-trimester needle embryofetoscopy (or embryoscopy) for prenatal diagnosis in a continuing pregnancy. STUDY DESIGN: A patient at risk for giving birth to an infant with Robert's syndrome was referred for prenatal diagnosis at 12 weeks of gestation. RESULTS: Transabdominal embryoscopy and amniocentesis were performed. Direct visualization of the embryo was achieved and no gross limb or facial abnormalities were seen. Chromosome studies of the amniotic fluid revealed a normal male 46, XY. Special studies with C-banding and DAPI techniques revealed no evidence of premature separation of centromeres. Two- and three-dimensional ultrasound also demonstrated no gross limb or facial abnormalities. CONCLUSIONS: This case confirms the efficacy of embryoscopy as a simple and relatively low-risk approach to first-trimester diagnosis for continuing pregnancies.

Adult↗
PubMedDate not supplied

Variable effects of different corticosteroids on plasma lipids, apolipoproteins, and hepatic apolipoprotein mRNA levels in rats.

Treatment of male rats with hydrocortisone provoked a dose- and time-dependent decrease in plasma cholesterol concentration without a change in plasma triglyceride levels. In contrast, administration of triamcinolone and dexamethasone at equipotent glucocorticoid doses increased plasma cholesterol and triglyceride levels, respectively. Small effects on apolipoprotein E (apo E) and apo B mRNA levels were observed, but all corticosteroids increased apo A-I and apo A-IV mRNA and decreased apo A-II mRNA levels in the liver. Triamcinolone and dexamethasone, however, were three times more potent in stimulating hepatic apo A-IV gene expression than was hydrocortisone, whereas liver apo A-I and apo A-II mRNA levels were altered to a similar extent by all corticosteroids. Plasma apo A-I and apo B concentrations always varied in a similar fashion with their respective liver mRNA levels after administration of the distinct corticoids. For apo A-IV and apo E, discrepancies between plasma and liver mRNA levels after administration of the different steroids, however, point to additional regulatory effects on plasma apolipoprotein levels. We conclude that 1) in contrast to plasma apo A-I and apo B, alterations in plasma lipid, apo A-IV, and apo E levels depend on the type of corticosteroid used; and 2) glucocorticoids have a differential effect on hepatic mRNA levels of apo A-I and apo A-IV on the one hand and apo A-II on the other hand, an effect that may be of consequence in the process of reverse cholesterol transport.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Weighted health status in the Medicare population: development of the Weighted Health Index for the Medicare Current Beneficiary Survey (WHIMCBS).

We present an approach to constructing an aggregate index of health at the population level with data from Medicare beneficiaries using the 1991 (N = 12,667), 1995 (N = 15,590), and 1997 (N=17,058) Medicare Current Beneficiary Survey (MCBS). Similar to other work with survey data, we develop a weighted health status index from which one can calculate a point in time health status score for any beneficiary. Scores range from 1.0, representing "excellent health and no activity limitation", to 0.0, representing deceased. Sequences of numerically weighted health states experienced over time can be summed to calculate years of healthy life for beneficiaries. We test both the stability of the scoring system when developed on independent samples, as well as the sensitivity of years of healthy life calculations to changes in scoring assumptions. Findings suggest that, in addition to mortality, morbidity appears to play a significant role in the years of healthy life accrued by Medicare beneficiaries since entry into the Medicare program. Further, the index scoring system is highly stable when derived on independent samples. Finally, calculations of years of healthy life are robust to changes in scoring assumptions. The weighted health index for Medicare current beneficiaries (WHIMCBS) is a stable overall index of health and may be a useful ongoing indicator of health within the Medicare population.

Activities of Daily Living↗
PubMedDate not supplied

Prophylactic antibiotics after severe trauma: more is not better.

After severe trauma, physicians frequently use multiple antibiotics for prolonged periods of time to prevent sepsis, based on intuition rather than scientific evidence. Over a 1-year period (January-December 1999) we included prospectively 112 critically injured patients who required an operation and/or chest tube insertion and stayed for more than 2 days in the intensive care unit (ICU). Of these patients, 46 received a single prophylactic antibiotic for 24 hours (group SING+SHORT), and 66 received one or more prophylactic antibiotics for more than 24 hours (group MULT+LONG), based on physician discretion. Twenty-seven outcome parameters were collected to compare the effect of the different prophylactic antibiotic regimens. The two groups were similar in regard to overall injury severity, age, gender, mechanism of injury, and physiologic condition on admission. However, more SING+SHORT patients had an abdominal operation (83% versus 62%, P = 0.02), and more MULT+LONG patients had an orthopedic operation (35% versus 15%, P = 0.03). There was no difference in sepsis (41% versus 42%, P = 1.0), organ failures (37% versus 50%, P = 0.18), mortality (7% versus 12%, P = 0.52), ICU stay (14 +/- 2.5 versus 16 +/- 2 days, P = 0.57), hospital stay (26 +/- 3 versus 28 +/- 2 days, P = 0.53), or any other outcome parameter. Independent risk factors for sepsis were blunt mechanism of trauma, Injury Severity Score > or = 25, and more than two units of blood transfused over the first 24 hours, but not the amount of prophylactic antibiotics given. In conclusion, we found that 24-hour prophylaxis with a single broad-antibiotic is as effective as prophylaxis for longer periods of time with multiple spectrum antibiotics for critically injured patients at high risk for sepsis.

Adult↗