Search PubMed⌕ Search

Biomedical subjects

N Nguyen

Publications and source records attributed to N Nguyen.

At least 91 records · Page 5Linked to original sources
PubMed1996

DNA-binding activities in Streptococcus gordonii: identification of a receptor-nickase and a histonelike protein.

Extraction of Streptococcus gordonii cells with the mild chaotropic agent, LiCl, drastically decreased DNA transforming ability, had little effect on viability, and released both DNA nicking and binding activities. Both activities were Mg2+ and Ca2+ independent and were not competence specific. Southwestern blot analysis of the extract identified putative surface proteins of 56 kDa and 68 kDa in strain Challis and Wicky, respectively. Extracts also contained a 10-kDa DNA-binding protein, designated HSgo, that belongs to the eubacterial histonelike class of proteins.

Amino Acid Sequence↗
PubMed1996

Acute cholecystitis. Does the clinical diagnosis correlate with the pathological diagnosis?

BACKGROUND: Most of the literature dealing with the surgical management of acute cholecystitis bases patient selection on pathological diagnosis, either exclusively or using it as a major selection criteria or as a confirmation of diagnosis. The purpose of this study was to examine the correlation between preoperative clinical findings, intraoperative gross findings, and postoperative pathological findings. METHODS: A retrospective review of 493 consecutive laparoscopic cholecystectomies performed by a single surgeon (RJF) in a single institution was done. Four different sets of criteria were used to define four groups of patients as having acute cholecystitis: (1) preoperative acute cholecystitis based on defined criteria (PA); (2) intraoperative gross findings of acute or subacute cholecystitis based on surgeon assessment of inflammation (IA); (3) initial pathological evaluation by a staff pathologist (IP); and (4) expert pathological (EP) review using strictly defined histological criteria. RESULTS: Of 41 patients, 40 (97.6%) were classified as having acute cholecystitis by IA, 21 (51.2%) by IP, and 17 (41.5%) by EP. Of the 75 patients classified as having acute cholecystitis by IA, 40 (53.0%) were classified acute by PA, 34 (45. 0%) by IP, and 17 (22.7%) by EP. Of the 72 IP patients, 34 (47.2%) were classified as acute by IA, 15 (20.8%) by EP, and 24 (33.3%) were PA. Of the 32 EP patients, 21 (65.6%) were classified as acute by IA, 14 (43.8%) by IP, and 18 (56.3%) were PA. CONCLUSION: The correlation between the pathological diagnosis and intraoperative findings is poor. Preoperative clinical findings of acute cholecystitis are highly reliable for predicting intraoperative gross findings. However, intraoperative findings of acute cholecystitis are commonly found in the absence of preoperative clinical signs. Recommendations for surgical therapy should be based on studies which use either operative findings or the preoperative clinical findings as the basis for patient selection.

Adolescent↗
PubMed1996

A high prevalence of occludable angles in a Vietnamese population.

PURPOSE: To assess the prevalence of occludable angles in a Vietnamese population. METHODS: The authors retrospectively reviewed the angle status in 482 Vietnamese patients who presented to a general ophthalmology practice. All angles were graded by a glaucoma specialist according to the Shaffer method. Patients were excluded if they had known glaucoma or narrow angles, or a history of trauma or intraocular surgery. RESULTS: A total of 29.5% of all patients surveyed and 47.8% of those 55 years of age or older had grade 0 to 2 angles. In the Framingham study, 3.8% of white patients 55 years of age or older had grade 0 to 2 angles. Of the patients in our study population, 8.5% had grade 0 to 1 angles and were considered at high risk for occlusion. CONCLUSIONS: Vietnamese patients have a much higher prevalence of narrow angles and a greater risk of angle-closure glaucoma than white patients.

Adolescent↗
PubMed1996

Trabeculectomy with intraoperative sponge 5-fluorouracil.

PURPOSE: To retrospectively assess the outcome of trabeculectomy surgery performed using intraoperative sponge 5-fluorouracil (5-FU) (50 mg/ml). METHODS: Trabeculectomy with intraoperative sponge 5-FU was performed on 140 eyes of 119 patients. The reduction in intraocular pressure (IOP), the number of supplementary postoperative injections, and any treatment complications were noted. RESULTS: The mean preoperative IOP was 25.7 +/- 8.6 mmHg. The mean postoperative IOP was 12.5 +/- 5.7 mmHg with a mean IOP reduction of 52 percent (P < 0.0001). One hundred twenty-one (86.4 percent) eyes required no postoperative glaucoma medications, with the mean number of glaucoma medications dropping from 2.5 +/- 1.1 before operation to 0.3 +/- 0.8 after operation (P < 0.001). One hundred five eyes received a mean of 5.3 +/- 2.7 postoperative 5-FU injections. There was no significant difference in final IOP or success rate between low- and high-risk eyes, but high-risk eyes seemed to require supplementary postoperative 5-FU. Corneal epithelial damage arose in 52 (37 percent) eyes and correlated strongly with postoperative 5-FU supplementation. CONCLUSION: Intraoperative sponge 5-FU is a reasonably safe and effective adjunct to trabeculectomy surgery.

Adolescent↗
PubMed1996

Neutrophilic spongiosis in pemphigus herpetiformis.

Pemphigus herpetiformis is a rare pemphigus variant with light microscopic features that have historically been described as either "acantholytic dermatitis herpetiformis" or as "eosinophilic spongiosis in pemphigus". The clinical features of this form of pemphigus are reminiscent of dermatitis herpetiformis; however, the direct immunofluorescence finding of epidermal inter-cellular IgG deposition is that of the pemphigus group. We report two patients with clinical presentations suggestive of dermatitis herpetiformis in whom the histopathologic features were those of a neutrophilic intraepidermal blistering disorder. Biopsies showed marked epidermal spongiosis with midepidermal acantholytic vesicles containing predominantly neutrophils and a few eosinophils. Direct immunofluorescence was positive for epidermal intercellular IgG; IgA deposition was not present. Neutrophilic spongiosis, in the absence of a prominent eosinophilic infiltrate, should be recognized as an early finding in some cases of pemphigus, and immunofluorescence studies are justified when this histologic feature is encountered in a skin biopsy.

Acantholysis↗
PubMed1996

Update on the subconjunctival THC:YAG (holmium) laser sclerostomy Ab externo clinical trial: a 4-year report.

BACKGROUND AND OBJECTIVE: This is a follow-up report on 103 THC:YAG (holmium) sclerostomies ab externo performed on 87 eyes of 81 patients. PATIENTS AND METHODS: The patients received pulse energies of 0.06 to 0.13 J (mean total energy 4.4 +/- 3.3 J, range 0.6 to 17.1 J). RESULTS: The estimated success rates with or without medication, and allowing a second procedure, were 44% at 2 years and 36% at 4 years. The mean preoperative intraocular pressure (IOP) was 29.7 +/- 11.4 mm Hg, and the mean postoperative IOP in the successful patients was 13.6 +/- 4.6 mm Hg (P < .01). Hypotony and iris incarceration were the most frequent early complications. CONCLUSIONS: Although holmium laser sclerostomy is a relatively straightforward procedure and offers some advantages over standard trabeculectomy in select cases, it currently has a number of drawbacks that limit its use.

Adolescent↗
PubMed1995

Long-term results of noncontact transscleral neodymium:YAG cyclophotocoagulation.

PURPOSE: To determine the long-term efficacy of noncontact transscleral neodymium:YAG (Nd: YAG) cyclophotocoagulation. METHODS: A retrospective analysis was made of 167 patients (173 eyes) with intractable glaucoma treated with noncontact Nd:YAG cyclophotocoagulation between December 1987 and November 1993, reviewing the treatment parameters, complications, and pre- and posttreatment intraocular pressure (IOP). The IOP was compared using a Student's t test, and the results were subjected to a Kaplan-Meier life-table analysis. Success was defined as an IOP of 22 mmHg or lower in the absence of phthisis and without having undergone any additional surgical procedures. RESULTS: Mean follow-up was 30.5 +/- 22.8 months. Mean preoperative IOP was 40.0 +/- 12.9 mmHg. Mean postoperative IOP was 19.8 +/- 11.4 mmHg (P < 0.05). The mean number of treatment sessions was 1.8 +/- 1.3 (range, 1-8) with 95 eyes (55%) having only one treatment. Kaplan-Meier survival analysis showed a probability of continued success at 3 years of approximately 73% and at 5 years of 45%. Complications included loss of two or more lines of Snellen visual acuity or one or more categories in the low-vision range (40%), phthisis (6.9%), epithelial defects (1.9%), and hyphema (0.6%). CONCLUSION: This study suggests that Nd:YAG transscleral cyclophotocoagulation provides a useful long-term reduction of IOP in eyes with advanced or complicated glaucoma, but there is a significant risk of visual loss associated with the procedure.

Adolescent↗
PubMed1995

Reversible cardiac failure in an adolescent after prolonged exposure to carbon monoxide.

We describe the case of an adolescent who developed a severe but fully reversible cardiac dysfunction with low blood levels of carboxy haemoglobin (COHb = 10%) after a prolonged exposure to carbon monoxide. A 15-year-old male was admitted with a Glasgow Coma Scale of 8/15 with suspected postictal state and postanoxic encephalopathy. The cardiorespiratory failure which he developed soon after admission mandated mechanical ventilation, inotropic support and ultimately left ventricular support by intra-aortic balloon counterpulsation. The cardiac dysfunction was documented by radionuclide imaging and echocardiography. The patient fully recovered without neurological deficit. A low blood COHb concentration is a poor safety indicator since high tissue levels of accumulated carbon monoxide can be associated with coma and fulminant cardiorespiratory failure requiring advanced life support facilities.

Accidents, Home↗
PubMed1995

EPG bidimensional data reduction.

A new method of electropalatographic (EPG) data reduction is proposed. It uses the so-called discrete cosine transform for representing an EPG pattern as a weighted sum of elementary 'pictures'. It is shown that several of these pictures can be considered as being articulatorily relevant. The respective contributions of these pictures to the spatial arrangement of the linguopalatal contacts are given by transform coefficients which are used here as a set of new EPG indices: the scaled sum of contacts index (SSU), the left-right asymmetry index (LRA), the alveolar-palatal index (APA) and the lateral-median index (LME). It is shown that the information extracted from an EPG pattern by means of these indices is maximised. Because of its robustness, this method could be usefully employed in studies on articulatory disorders.

Electrodiagnosis↗
PubMed1995

Splenic avulsion in a pregnant patient with vomiting.

Splenic avulsion in pregnancy is a rare condition that carries a high risk of death to both mother and fetus. The authors describe a 30-year-old woman with hyperemesis who had spontaneous avulsion of the spleen at 30 weeks' gestation. She underwent a splenectomy and cesarean section, resulting in a stillborn fetus. The authors theorize that violent vomiting resulted in splenic avulsion. Prompt surgical intervention by a general surgeon and obstetrician is required in such cases.

Adult↗
PubMed1995

Topical and subcutaneous alpha-interferon fails to suppress corneal neovascularization.

Corneal neovascularization is a potentially blinding complication of a variety of corneal disorders. alpha-Interferon has been shown to inhibit endothelial cell migration and proliferation. It has been used successfully in the treatment of pediatric pulmonary hemangioma and hairy cell leukemia. This study was undertaken to evaluate the effect of topical and subcutaneous (s.c.) alpha-interferon on corneal neovascularization. Corneal neovascularization was induced in 40 male New Zealand white rabbits by placing silk sutures (7.0) bilaterally in each rabbit eye at the 3 and 9 o'clock positions of the cornea, 3 mm from the limbus. Animals were randomized into two main treatment groups for topical (group 1) and s.c. (group 2) administration of interferon. Group 1 (n = 24) was then randomized into four subgroups and treated daily with topical doses of (a) rabbit specific alpha-interferon; (b) alpha-interferon plus 1% prednisolone acetate; (c) 1% prednisolone acetate; and (d) buffered phosphate control. Group 2 (n = 16) was randomized into two subgroups that received s.c. injections every other day of (a) alpha-interferon and (b) phosphate buffer. Rate of corneal neovascularization was documented photographically, with the end-point being the arrival of vessels at the suture for each group. The results of this study indicated that at the concentration and dosing regimens we used, neither topical nor s.c. alpha-interferon inhibits the rate of corneal vascular growth significantly when compared with our phosphate buffered solution control group (p = 0.88 and p = 0.84, respectively). Prednisolone acetate appeared to be the most effective in inhibiting corneal neovascularization (p = 0.003).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1994

Bromodeoxyuridine-mediated radiosensitization in human glioma: the effect of concentration, duration, and fluoropyrimidine modulation.

PURPOSE: To define the relative influence of duration of exposure, concentration, and modulation by fluorodeoxyuridines (FdUrd) on the incorporation of 5-bromo-2-deoxyuridine (BrdUrd) into DNA of a human malignant glioma line (D-54) in vitro and in vivo. MATERIALS AND METHODS IN VITRO STUDIES: an established human malignant glioma line (D-54) was exposed to a clinically achievable concentration of BrdUrd to model intravenous (1 microM BrdUrd) and intraarterial (4 microM BrdUrd) conditions. The influence of modulation was assessed using 1 nM FdUrd. Incorporation of BrdUrd, radiosensitization, and cytotoxicity were determined after 24, 72, and 120 h drug exposures. In Vivo studies: nude mice bearing D-54 xenografts were infused with BrdUrd at 100 mg/kg/day for 7 and 14 days or BrdUrd at 400 mg/kg/day for 5 days. The influence of modulation was assessed by combining 100 mg/kg/day of BrdUrd with 0.1, 0.3, and 1 mg/kg/day FdUrd for 7 days. Incorporation of BrdUrd into the DNA of tumor, gut, and marrow were determined. RESULTS: In Vitro: thymidine replacement and radiosensitization were a function of concentration, and incorporation began to plateau after 2 to 3 population doublings. Modulation with 1 nM FdUrd significantly increased incorporation. Radiosensitization was a linear function of thymidine replacement under all conditions tested. In Vivo: infusion with 400 mg/kg/day for 5 days resulted in greater tumor incorporation (10.3 +/- 0.4% thymidine replaced) than treatment with 100 mg/kg/day for 14 days (6.0 +/- 0.6% of thymidine replaced). Infusion of FdUrd with BrdUrd increased normal tissue incorporation of BrdUrd, but failed to increase BrdUrd incorporation in tumor cells. CONCLUSION: These results suggest that relatively short, high dose rate infusions may be preferable to long, low dose rate infusions. The potential benefit of FdUrd modulation demonstrated in vitro may be difficult to realize using continuous systemic infusions.

Animals↗
PubMed1994

Quantitation of hepatitis B virus DNA in serum by ammonium sulfate precipitation and molecular hybridization.

We developed a method to quantitate hepatitis B virus (HBV) DNA in serum by ammonium sulfate fractionation and DNA hybridization. Serum samples were precipitated with 45% saturated ammonium sulfate, resuspended in buffer, and spotted on a nylon membrane. Following denaturation in alkali, HBV DNA sequences on the membrane were detected by hybridization with a 32P-labeled DNA probe of the entire HBV genome. Bound radioactivity was measured with liquid scintillation counting. Ammonium sulfate fractionation of positive samples increased assay sensitivity by 10-30-fold compared to no treatment. Sensitivity for detection of cloned HBV DNA added to negative serum was 0.2 pg. Recovery of cloned HBV DNA added to negative serum before fractionation was equivalent to direct spotting of DNA onto the membrane in the absence of serum. This method enhanced HBV DNA recovery from serum into small volumes, thereby expanding the potential analytic range of spot hybridization assays.

Adult↗
PubMed1994

Imaging of cardiac neuronal function after cocaine exposure using carbon-11 hydroxyephedrine and positron emission tomography.

OBJECTIVES: The aim of the study was to define the effect of cocaine on the myocardial uptake and retention of C-11 hydroxyephedrine in the anesthetized dog model. BACKGROUND: Cardiac toxicity of cocaine has been linked to its inhibitory effect on norepinephrine reuptake by the sympathetic nerve terminals of the heart. Carbon-11 hydroxyephedrine is a C-11-labeled norepinephrine analog that has high specific affinity for uptake-1 and thus makes possible the assessment of the effect of cocaine on norepinephrine reuptake by cardiac sympathetic nerve terminals. METHODS: The cardiac kinetics of C-11 hydroxyephedrine as assessed by dynamic positron emission tomographic imaging were used to characterize norepinephrine reuptake by the sympathetic nerve terminals. Carbon-11 hydroxyephedrine was injected intravenously before, as well as at 5 min and 2.5 h after, intravenous administration of 2 mg/kg body weight of cocaine in anesthetized dogs. Hemodynamic variables and microsphere-determined cardiac blood flow were also measured before and after cocaine exposure. RESULTS: Intravenous injection of cocaine did not significantly affect hemodynamic variables and myocardial blood flow in the anesthetized animals. Compared with baseline, myocardial retention of C-11 hydroxyephedrine was significantly reduced by 78 +/- 3% (mean +/- SD) at 5 min and remained significantly reduced (28 +/- 17%) at 2.5 h after cocaine injection. Cocaine administration after C-11 hydroxyephedrine injection (30 min) resulted in rapid biexponential clearance of C-11 hydroxyephedrine from myocardium. CONCLUSIONS: These results suggest prolonged effects of cocaine on the sympathetic nerve terminals of the heart. Positron emission tomography provides a noninvasive and sensitive means to objectively assess the cardiac pharmacokinetics of drugs such as cocaine.

Animals↗
PubMed1994

Ischemia induces translocation of the insulin-responsive glucose transporter GLUT4 to the plasma membrane of cardiac myocytes.

BACKGROUND: Acute myocardial ischemia is accompanied by an increase in glucose uptake and metabolism, which appears to be important in protecting myocardial cells from irreversible ischemic injury. Because insulin augments myocardial glucose uptake by inducing the translocation of glucose transporters from an intracellular compartment to the plasma membrane, we hypothesized that acute ischemia would trigger a similar translocation. METHODS AND RESULTS: We used a subcellular fractionation method to separate intracellular membrane and plasma membranes from control, ischemic, and hypoxic Langendorff-isolated perfused rat hearts and determined the expression of the major myocardial glucose transporter, GLUT4, in these separated membrane fractions. We found that translocation of GLUT4 molecules occurred in ischemic, hypoxic, and insulin-treated hearts and in hearts that underwent ischemia plus insulin treatment. The percentages of GLUT4 molecules present on the plasma membrane in the different conditions were as follows: control, 18.0 +/- 2.8%; ischemia, 41.3 +/- 9.4%; hypoxia, 31.1 +/- 2.9%; insulin, 61.1 +/- 2.6%; and ischemia plus insulin, 66.8 +/- 5.7%. Among the statistically significant differences in these values were the difference between control and ischemia and the difference between ischemia alone and insulin plus ischemia. CONCLUSIONS: Ischemia causes substantial translocation of GLUT4 molecules to the plasma membrane of cardiac myocytes. A combination of insulin plus ischemia stimulates an even greater degree of GLUT4 translocation. GLUT4 translocation is likely to mediate at least part of the increased glucose uptake of ischemic myocardium and may be a mechanism for the cardioprotective effect of insulin during acute myocardial ischemia.

Animals↗
PubMed1994

Laparoscopic inguinal herniorrhaphy.

Currently accepted laparoscopic inguinal herniorrhaphies are of three types: Trans-Abdominal Pre-Peritoneal (TAPP), Intra-Peritoneal Onlay Mesh (IPOM), and Totally Extra-peritoneal (EXTRA). The TAPP procedure is the most commonly performed operation. The peritoneum is opened transversely above the hernia defect and a radical dissection of the pre-peritoneal space accomplished. The hernia defect is widely covered with a large prosthesis, and the mesh is secured with staples. The peritoneum is then closed over the prosthesis. The IPOM technique has become the second most common laparoscopic inguinal herniorrhaphy. A prosthesis is placed on the intra-abdominal side of the peritoneum and stapled in place using the same landmarks as for the TAPP. This avoids an extensive dissection of the pre-peritoneal space. However, it must be considered as an experimental procedure because of the possibility of complications caused by adhesions to the intra-abdominally placed prosthesis. The third type of laparoscopic inguinal herniorrhaphy is the EXTRA. The hernia is repaired using laparoscopic instrumentation without violating the peritoneum by dissecting the space between the peritoneum and the transversalis fascia, beginning at the umbilicus. Once the inguinal region is entered, the procedure is similar to the TAPP. However, it is more difficult than the TAPP because of the small working space, especially for the inexperienced. Early results suggest that laparoscopic inguinal herniorrhaphy is an effective method for correcting an inguinal hernia. It can be performed with a reasonably low morbidity. Indications remain to be determined. A randomized prospective study comparing laparoscopic inguinal herniorrhaphy with conventional is warranted.

Hernia, Inguinal↗
PubMed1993

Halogenated pyrimidine sensitization of low dose rate irradiation in human malignant glioma.

PURPOSE: To determine the potential advantage of combining halogenated pyrimidine radiosensitization and continuous low dose rate irradiation in human malignant glioma. METHODS AND MATERIALS: An established glioma line (U-251) was incubated with 5-bromo-2-doxyuridine (BrdUrd) at clinically achievable concentrations at three dose rates of interest--100 cGy/min (typical of external beam therapy), 43 cGy/hr (typical of temporary afterloaded implants), and 12 cGy/hr (typical of permanent implants). RESULTS: After exposure to 1 microM BrdUrd, the greatest enhancement ratio was seen at the 12 cGy/hr dose rate, implying a BrdUrd induced inverse dose rate effect independent of a G2M block. Under these conditions, the mean inactivation dose after 1 microM BrdUrd exposure was equivalent for 100 cGy/min and 12 cGy/hr. CONCLUSION: These results support the use of halopyrimidines as sensitizers of temporary afterloaded and permanent implants.

Bromodeoxyuridine↗