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Biomedical subjects

L Nguyen

Publications and source records attributed to L Nguyen.

160 records · Page 9Linked to original sources
PubMed1982

Hepatic hemangioma in childhood: medical management or surgical management?

Between 1955 and 1980 there were 14 patients treated at The Hospital for Sick Children with hemangiomas of the liver. Eight were seen at birth and 13 within the first 6 wk of life. The presenting clinical feature was that of massive hepatomegaly. Two children who had presented in the neonatal period were found to have had cardiac failure. Six patients were anemic and required blood transfusions. Before 1976 all patients who did not have cutaneous hemangiomas underwent laparotomy. Since 1976 only one laparotomy was done, the remaining 5 patients all having been treated symptomatically without operation. All the tumors involuted in the first year of life. Follow-up ranged from 1 to 20 yr and all are living and without symptoms. We recommend no active treatment if complications are absent. Steroids and radiotherapy are not used. If anemia and/or cardiac failure supervene, appropriate nonoperative management is necessary. Surgical treatment is indicated only if medical management fails or for rupture of the lesion.

Child↗
PubMedDate not supplied

Effects of intravenous and oral dexamethasone on selected lymphocyte subpopulations in normal subjects.

Our studies describe the effects of 1 mg oral (PO) and intravenous (IV) administration of dexamethasone (DEX) on certain subpopulations of circulating lymphocytes in normal subjects. We compared the outcomes of PO and IV DEX administration because of individual differences in gastro-intestinal absorption of DEX and the issue of noncompliance in patients undergoing the dexamethasone suppression test (DST). Both routes of DEX administration were equally effective in suppressing plasma cortisol levels below 5 micrograms/dl, the customary criterion level. Both routes of DEX administration also significantly decreased the percent and absolute number of CD4+ cells, the CD4+/CD8+ ratio, and the percent and absolute number of virgin, but not of memory, CD4+ cells.

Administration, Oral↗
PubMedDate not supplied

Panic disorder among Vietnamese refugees attending a psychiatric clinic: prevalence and subtypes.

This study surveys Vietnamese refugees attending two psychiatric clinics to determine both the prevalence of panic disorder (PD) as well as panic attack subtypes in those suffering PD. A culturally valid adaptation of the SCID-panic module (the Vietnamese Panic Disorder Survey or VPDS) was administered to 100 Vietnamese refugees attending two psychiatric clinics. Utilizing culturally sensitive panic probes, the VPDS provides information regarding both the presence of PD and panic attack subtypes during the month prior to interview. Of 100 patients surveyed, 50 (50%) currently suffered PD. Among the 50 patients suffering PD, the most common panic attack subtypes during the previous month were the following: "orthostatic dizziness" (74% of the 50 panic disorder patients [PDPs]), headache (50% of PDPs), wind-induced/temperature-shift-induced (24% of PDPs), effort-induced (18% of PDPs), gastro-intestinal (16% of PDPs), micturition-induced (8% of PDPs), out-of-the-blue palpitations (24% of PDPs), and out-of-the-blue shortness of breath (16% of PDPs). Five mechanisms are adduced to account for this high PD prevalence as well as the specific profile of subtypes: 1) a trauma-caused panic attack diathesis; 2) trauma-event cues; 3) ethnic differences in physiology; 4) catastrophic cognitions generated by cultural syndromes; and 5) a modification of Clark's spiral of panic.

Ambulatory Care↗
PubMedDate not supplied

Unexpected failure of bile acid malabsorption to stimulate cholesterol synthesis in sitosterolemia with xanthomatosis. Comparison with lovastatin.

We examined the relationship between cholesterol synthesis and high affinity low density lipoprotein (LDL) catabolism in freshly isolated mononuclear leukocytes and plasma sterols and apolipoprotein concentrations in three homozygous and one heterozygous subject with sitosterolemia with xanthomatosis and in 12 control subjects. Observations in untreated subjects were compared during therapy with lovastatin or interruption of the enterohepatic circulation of bile acids. Plasma cholesterol, plant sterol, and apolipoprotein B concentrations declined more than 50% in the two homozygous sitosterolemic subjects after ileal bypass surgery. In contrast, plasma cholesterol, plant sterol, and apolipoprotein B concentrations remained constant in a homozygous sitosterolemic subject and declined only 7% in a heterozygous sitosterolemic subject during 20 weeks of lovastatin (40 mg/day) treatment compared to a 28% decrease in similarly treated control subjects. Lovastatin treatment decreased cholesterol synthesis more than 60% but did not increase high affinity catabolism of LDL further in the sitosterolemic cells, compared to a more than 20% rise in control mononuclear leukocytes. Conversely, bile acid malabsorption increased cholesterol synthesis 59%, total hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase activity 13%, and receptor-mediated LDL degradation 41% in control cells, but did not stimulate cholesterol synthesis or microsomal HMG-CoA reductase activity in sitosterolemic mononuclear leukocytes although receptor-mediated LDL catabolism rose an additional 26%. These results demonstrate a greater than expected decrease in plasma sterols and apolipoprotein B concentrations in sitosterolemic subjects after stimulation of bile acid synthesis because of the inability to up-regulate cholesterol production. We suggest that bile acid-sequestering drugs or ileal exclusion surgery may be more effective treatments to mobilize accumulated sterol deposits and prevent atherosclerosis in this disease.

Adult↗
PubMedDate not supplied

Automated electrocardiogram analysis: the state of the art.

The overwhelming number of electrocardiograms (ECGs) now recorded routinely has prompted the development of computer analysis which in turn has benefited electrocardiography with important technological advances. All automated ECG analysis systems adopt a similar approach: a measurement program and a program that interprets the clinical significance of these measurements along with a rhythm analysis algorithm. Measurement, selection and classification of parameters vary according to the program used. Data compression is applied to the signal to reduce processing time and allow long-term storage. Diagnostic accuracy, however, is not greatly improved over that of experienced cardiologists. Programs studied using a validated data bank provided by an international group of cardiologists show a variability not only in parameter measurement but also in diagnostic statement and in the way in which such statements are expressed. Recommendations for measurement standards have been made to fulfil the need for exchange of diagnostic criteria. No recommendations concerning the selection of parameters have been proposed, and so new parameters or combinations of parameters can be introduced with the ultimate aim of increased diagnostic performance.

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

Pharmaceutical container/closure integrity. V: An evaluation of the WILCO "LFC" method for leak testing pharmaceutical glass-stoppered vials.

The sensitivity, reliability, reproducibility and ease of use of the WILCO LFC package integrity test method was evaluated by preparing and testing a series of rubber-stoppered glass vials which were modified by affixing a glass micropipette through the vial side wall. The test units contained water, 50% aqueous ethanol, 20% lithium chloride or 20% aqueous glycerol. Leakage measurement obtained by LFC testing were compared to helium leak rate measurements. The LFC methods detected all leak > 0.0014 standard cubic centimeters per second (sccs), which represents a sensitivity about fourteen-fold greater than standard vacuum decay methods. The minimum detectable leak corresponded to a nominal micropipette internal diameter of between 1 and 2 microns. The effective detection range corresponded to a leak size associated with a 40 to 100% probability of microbial ingress based on a previously reported logistical regression model between helium leak rate and microbial immersion. The sensitivity did not vary with solvent or testing duration in range of 5 to 10 seconds. The coefficient of variation was about 3%. The LFC operation was rapid and without apparent mechanical or electronic problems over the two day testing period used in these studies.

Drug Packaging↗
PubMedDate not supplied

The economics of central billing offices.

The anticipation of economies of scale in physician billing has led many medical practices to consolidate their billing operations. This article analyzes these economies of scale, comparing performance indicators from centralized and decentralized operations. While consolidation provides compliance, control and information, diseconomies of scale can exist in the centralized receivables management process. The authors conclude that physician practices should consider a hybrid approach to billing, thus reaping the benefits of both centralization and decentralization.

Accounts Payable and Receivable↗
PubMedDate not supplied

[Evaluation of the efficacy of mannitol in the treatment of ciguatera in French Polynesia].

Up till now, in the French Polynesia and in New Caledonia, people showing ciguatera intoxication receive a standard treatment: calcium + vitamins B6 and C by intravenous way and in addition, some drugs arriving to cure some symptomatic manifestations. In 1988, an investigation carried out in Majuro, Marshall Islands concluded that intravenous mannitol is efficient in the treatment of serious intoxications with suspecting cerebral oedema. Since, such a treatment has been utilized with success in several endemic areas. Our therapeutic evaluation was arrived to determine whether mannitol's efficiency is higher than the standard treatment in the ciguatera intoxications of mean seriousness. This investigation was carried out on two randomized groups: The first one receiving mannitol (250 cc intravenous at 20% injected in 1 h) the second one receiving the standard treatment (intravenous perfusion glucose serum 250 cc with 1 g of vitamins C, 250 mg of vitamin B6 and 1 g of calcium gluconate injected in 1 h). Seriousness of clinical status was evaluated according to a scale of score from 0 to 50, based on the importance of the clinical manifestations paresthesia, aches, asthenia, cardiovascular and digestive signs. Only patients getting a score at least 20 were included in this investigation. Clinical status of each patient was evaluated before any treatment (initial score) at the end of perfusion and at the 24th hour. Efficiency of each treatment respectively was evaluated according to the differences between these three different scores. CHI 2 and U Mann's and Whitney's tests were utilized for the statistical analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Phenotypic properties and cytotoxic functions of human CD8+ cells expressing the CD57 antigen.

The CD8+CD57+ granular lymphocyte subset is significantly expanded in a number of clinical disorders. Because several studies have suggested that CD8+CD57+ cells might be in vivo primed, antigen-specific cytotoxic T lymphocytes, we have analyzed the phenotypic and functional properties of CD8+CD57+ cells. Using three-color flow cytometry, virtually all freshly isolated CD3+CD8+CD57+ cells were found to have phenotypic properties characteristic of 'naive' T lymphocytes; these cells coexpressed the CD45RA antigen, lacked expression of the CD45RO antigen, and expressed reduced levels of CD58 adhesion molecules. When purified CD45RA+ T cells were stimulated with alloantigens, approximately 50% of CD8+CD57- cells lost CD45RA antigen expression. In contrast, CD8+CD57+ cells (which were > 90% CD3+) remained CD45RA+. Although CD8+CD57+ cells could mediate lectin-dependent cytotoxicity, both before and after the mixed lymphocyte reaction cultures, CD8+CD57+ cells had no antigen-specific cytotoxic activity against allogeneic target cells; only the subset of CD8+CD57- cells which converted to the CD45RA- phenotype had specific cytotoxic activity. Interestingly, although CD8+CD57+ cells did not lyse allogeneic cells, 50-90% of these cells acquired HLA-DR antigen expression during the mixed lymphocyte reaction. This did not appear to be a passive effect produced solely by lymphokines, because soluble factors released by alloactivated T cells induced only modest HLA-DR expression on purified CD8+CD57+ cells. Thus, whereas CD8+CD57+ cells may become activated when in the milieu of an immunologically specific response, our data suggest that these cells do not develop into or appear to represent antigen-specific cytotoxic T cells.

Antigens↗
PubMedDate not supplied

Interactions between tissues engaged in wound repair and skeletal muscle regeneration.

Enhanced accumulation of granulation tissue in a wound healing model was observed in the presence of regenerating skeletal muscle. This study characterized the tissue accumulated in the normal wound healing and regeneration-adapted models. DNA, RNA, total protein, collagen, and noncollagen protein content, and protein:DNA and noncollagen protein:collagen ratios were determined using standard methods. DNA did not differ; but RNA increased and total protein decreased compared to early granulation tissue. Mean protein: DNA ratio was lower in regeneration-associated granulation tissue compared to age-matched normal and early granulation tissue. Collagen was reduced and noncollagen protein was increased in tissue surrounding regenerating muscle, yielding an elevated noncollagen:collagen ratio. The relative cellularity of granulation tissue was enhanced and collagen deposition potentially reduced, when accompanied by regeneration. Factors from a regeneration environment can interact with cells engaged in wound repair and potentially alter their behavior.

Animals↗
PubMedDate not supplied

Pharmaceutical container/closure integrity. I: Mass spectrometry-based helium leak rate detection for rubber-stoppered glass vials.

The development of mass spectrometry-based leak detection for pharmaceutical container integrity was undertaken to provide an alternative to microbial challenge testing. Standard 10-mL vials were modified to contain pinholes (0.5 to 10 microns) by affixing micropipettes with epoxy into 2-mm vial side wall holes. The absolute leak rate was determined using vials that were sealed in a tracer (helium) environment with butyl rubber stoppers and crimps. Alternatively leak rates were determined using vials that were sealed in room air and exposed to tracer under pressure (charging or bombing). Tracer leak rates were measured with mass spectrometry leak rate detectors. The absolute leak rate was correlated the squared nominal leak radius which suggested that the mode of gas flow through the glass pipette leaks was more turbulent than viscous even at low leak rates typically associated with viscous flow. The minimum observed absolute leak rate was about 10(-6.6) std cc/sec and was likely due to helium permeation through the rubber stoppers. Heat-stressed rubber stoppers did not affect the baseline absolute leak rate. Adsorption of helium tracer to the test unit surfaces was found to confound baseline leak rate measurement reliability but was eliminated as a source of variation by exposing the test units to ambient air for > or = 12 hours. The absolute leak rate and the leak rate measured after charging were related in a mathematically predictable way.

Drug Packaging↗
PubMedDate not supplied

Pharmaceutical container/closure integrity. II: The relationship between microbial ingress and helium leak rates in rubber-stoppered glass vials.

Helium leak rate measurements were quantitatively correlated to the probability of microbial ingress for rubber-stoppered glass vials subjected to immersion challenge. Standard 10-mL tubing glass vials were modified by inserting micropipettes of various sizes (0.1 to 10 microns nominal diameter) into a side wall hole and securing them with epoxy. Butyl rubber closures and aluminum crimps were used to seal the vials. The test units were sealed in a helium-filled glove bag, then the absolute helium leak rates were determined. The test units were disassembled, filled with media, resealed, and autoclaved. The test units were thermally treated to eliminate airlocks within the micropipette lumen and establish a liquid path between microbial challenge media and the test units' contents. Microbial challenge was performed by immersing the test units in a 35 degrees C bath containing magnesium ion and 8 to 10 logs of viable P. diminuta and E. coli for 24 hours. The test units were then incubated at 35 degrees C for an additional 13 days. Microbial ingress was detected by turbidity and plating on blood agar. The elimination of airlocks was confirmed by the presence of magnesium ions in the vial contents by atomic absorption spectrometry. A total of 288 vials were subjected to microbial challenge testing. Those test units whose contents failed to show detectable magnesium ions were eliminated from further analysis. At large leak rates, the probability of microbial ingress approached 100% and at very low leak rates microbial ingress rates were 0%. A dramatic increase in microbial failure occurred in the leak rate region 10(-4.5) to 10(-3) std cc/sec, which roughly corresponded to leak diameters ranging from 0.4 to 2 microns. Below a leak rate of 10(-4.5) std cc/sec the microbial failure rate was < 10%. The critical leak rate in our studies, i.e. the value below which microbial ingress cannot occur because the leak is too small, was observed to be between 10(-5) and 10(-5.8) std cc/sec, which corresponds to an approximate leak diameter of 0.2-0.3 micron.

Drug Contamination↗
PubMedDate not supplied

Pharmaceutical container/closure integrity. III: Validation of the helium leak rate method for rigid pharmaceutical containers.

Validation of a helium leak rate method for pharmaceutical container/closure integrity quality assurance required the demonstration that this physical testing method was as good or better than microbial immersion challenge testing in detecting potential integrity failures. One lot of rubber-stoppered, broth-filled glass vials also containing defective vials with known leaks were subjected to both helium leak rate and microbial challenge testing. The defective vials were prepared by affixing glass micropipettes (0.1 to 10 microns) into the vial side walls. The validation lot included a 10% seeded defect rate of which about 50% contained leaks with a predicted probability of failing a microbial challenge (> 10%). Helium tracer was placed in the test units by charging them for 4 hours under a 40 psi helium pressure. The critical leak rate after charging was determined to be 10(-7) standard cc/second, and test units with measured leak rates greater than this value were considered helium leak rate failures. Microbial immersion challenge was conducted by exposing the test units in a bath inoculated with 10(9-10) viable E. coli and B. diminuta organisms for 24 hours followed by a 13 day (35 degrees C) incubation. Microbial failures were determined visually. The helium and microbial leak test methods were compared statistically using mean failure rates. The mean helium failure rate was 6.9%, whereas the mean microbial failure rate was 2.8%. The difference between helium and microbial failure rates was significantly greater than zero. Thus, helium leak rate testing was demonstrated to be a suitable pharmaceutical container/closure integrity method for microbial quality assurance of rigid containers.

Drug Packaging↗