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Biomedical subjects

H Nguyen

Publications and source records attributed to H Nguyen.

At least 217 records · Page 12Linked to original sources
PubMed1990

The distribution and cellular localization of the serotonin 1C receptor mRNA in the rodent brain examined by in situ hybridization histochemistry. Comparison with receptor binding distribution.

The regional distribution and cellular localization of mRNA coding for the serotonin 1C receptor were investigated in tissue sections of mouse and rat brain by in situ hybridization histochemistry. Several 32P-labelled riboprobes derived from mouse genomic clones were used. The serotonin 1C receptor binding sites were visualized autoradiographically and quantified using [3H]mesulergine as ligand, in the presence of spiperone to block serotonin 1C receptors. Strong hybridization signal was observed in the choroid plexus of all brain ventricles. High levels of hybridization were also seen in the anterior olfactory nucleus, pyriform cortex, amygdala, some thalamic nuclei, especially the lateral habenula, the CA3 area of the hippocampal formation, the cingulate cortex, some components of the basal ganglia and associated areas, particularly the nucleus subthalamicus and the substantia nigra. The midbrain and brainstem showed moderate levels of hybridization. The distribution of the serotonin 1C receptor mRNA corresponded well to that of the serotonin 1C receptors. The highest levels of serotonin 1C receptor binding were observed in the choroid plexus. In addition, significant levels of the serotonin 1C receptor binding were seen in the anterior olfactory nucleus, pyriform cortex, nucleus accumbens, ventral aspects of the striatum, paratenial and paracentral thalamic nuclei, amygdaloid body and substantia nigra pars reticulata. The cingulate and retrosplenial cortices as well as the caudal aspects of the hippocampus (CA3) were also labelled. Binding in brainstem and medulla was low and homogeneously distributed. No significant binding was seen in the habenular and subthalamic nuclei. Similar findings were obtained in rat brain. These results demonstrate that, in addition to their enrichment in the choroid plexus, the serotonin 1C receptor mRNA and binding sites are heterogeneously distributed in the rodent brain and thus could be involved in the regulation of many different brain functions. The combination of in situ hybridization histochemistry with receptor autoradiography opens the possibility of examining the regulation of the serotonin 1C receptor synthesis after pharmacological or physiological alterations.

Animals↗
PubMed1990

Mononuclear leukocyte glucocorticoid receptor binding characteristics and down-regulation in major depression.

Some patients with major depressive disorder (MDD) have elevated plasma cortisol concentrations and show failure to suppress cortisol secretion upon administration of dexamethasone (DEX), yet they do not have Cushingoid features. To study whether this represents glucocorticoid (GC) resistance, [3H]-DEX-binding assays were used to measure, in vitro, the GC receptor affinity (1/Kd) and number (Bmax) in mononuclear leukocytes of 11 MDD patients and 15 control subjects. No receptor abnormalities were detected in the MDD group; thus any cellular defect leading to a lack of responsiveness to GC in the MDD patients, if present, probably lies beyond the initial receptor binding. DEX (1.0 mg orally) was administered to study in vivo GC receptor down-regulation. Compared to the control group, fewer depressed subjects down-regulated Bmax after DEX. By paired t-test, Bmax decreased significantly in the control group but not in the depressed group. Receptor number on the control day did not correlate significantly with the degree of receptor down-regulation, severity of depression or cortisol concentrations across all the subjects. These results do not lend support to previous reports suggesting that GC resistance in MDD results from a GC receptor-binding abnormality, and they emphasize the importance of considering receptor studies in the context of GC-mediated cell processes in order to identify the exact cellular defect(s) leading to GC resistance.

Administration, Oral↗
PubMed1990

True incidence of pacemaker syndrome.

Although the purported incidence of pacemaker syndrome according to the literature is only 5%-15%, this is based on a series of patients with VVI pacing. Increasing numbers of studies are being reported in which patients prefer the dual chamber mode despite little benefit being demonstrated on objective testing, suggesting that pacemaker syndrome may be more common than is generally reported. This study was designed to evaluate the reported symptoms in a series of patients programmed to both the VVI and one or more dual chamber modes. Forty unselected patients with dual chamber pacemakers were entered into a blind, randomized trial comparing the symptoms associated with VVI pacing to those associated with dual chamber pacing. Patients were randomized to either VVI or dual chamber pacing. At the end of 1 week, questionnaires rating 16 different symptoms were completed. Blood pressure, LV function, presence of ventriculoatrial conduction, and ability to override the pacemaker were evaluated. The pacemaker was then programmed to the other mode. Overall, 12 of 16 symptoms were significantly worse in the VVI as compared to dual chamber mode. The most highly significant (P less than 0.005) were shortness of breath, dizziness, fatigue, pulsations in the neck or abdomen, cough, and apprehension. Pacemaker syndrome was clinically recognized in 83% of patients paced in the VVI mode with 65% of patients experiencing moderate to severe symptoms. There were no readily identified clinical, hemodynamic, or electrophysiological parameters that predicted which patients would develop pacemaker syndrome. Thus, when patients have an opportunity to experience both pacing modes in close proximity to one another, there is a high incidence of pacemaker syndrome in the VVI mode.

Aged↗
PubMed1990

In vitro activity of LY264826, a new glycopeptide antibiotic, against gram-positive bacteria isolated from patients with cancer.

The in vitro activity of LY264826, a novel glycopeptide antibiotic produced by Amycolatopsis orientalis, was compared with those of vancomycin, teicoplanin, and oxacillin against 311 gram-positive clinical isolates from patients with cancer, LY264826 had lower MICs for 90% of isolates (MIC90) than vancomycin for all species tested. It was active against oxacillin-resistant isolates including Staphylococcus aureus (MIC90, 0.5 micrograms/ml), Staphylococcus haemolyticus (MIC90, 2.0 micrograms/ml), Enterococcus spp. (MIC90, 0.5 micrograms/ml), Bacillus cereus (MIC90, 0.25 micrograms/ml), and Corynebacterium jeikeium (MIC90, 0.12 micrograms/ml). For S. aureus, including oxacillin-resistant isolates, the MICs of LY264826 were similar to those of teicoplanin. For coagulase-negative staphylococci, however, LY264826 had MICs that were 4- to 32-fold lower than those of teicoplanin. Against most streptococcal species the activities of LY264826 and teicoplanin were similar. Bactericidal activity against Staphylococcus spp. and most Streptococcus pyogenes isolates was less than or equal to 1 dilution of the MIC. One isolate of S. pyogenes and all Enterococcus faecalis strains tested were tolerant of LY264826, with MBCs greater than or equal to 32-fold greater than the MICs. The addition of 50% human serum resulted in a significant increase in activity only against Staphylococcus epidermidis. Variations in pH from 6.4 to 8.4 and in inoculum from 10(3) to 10(7) CFU/ml did not significantly affect the activity of LY264826.

Anti-Bacterial Agents↗
PubMed1990

In vitro activity of sparfloxacin (CI-978; AT-4140) against clinical isolates from cancer patients.

The in vitro activity of sparfloxacin, a new quinolone, was compared with those of ciprofloxacin and fleroxacin against gram-positive and gram-negative bacteria, greater than 90% of which were isolated from blood culture specimens of cancer patients. Sparfloxacin was extremely active against Acinetobacter species, Aeromonas hydrophila, Citrobacter diversus, Enterobacter species, Escherichia coli, Klebsiella species, Proteus vulgaris, and Serratia marcescens (inhibiting greater than 90% of these isolates at a concentration of 0.5 microgram/ml) and moderately active against Pseudomonas species, other Proteus species, and Citrobacter freundii. Sparfloxacin inhibited greater than 90% of staphylococci (including methicillin-resistant and coagulase-negative strains) at a concentration of 0.12 microgram/ml and greater than 90% of streptococci (including Streptococcus pneumoniae) at a concentration of 1.0 microgram/ml. It was also active against Bacillus cereus, Enterococcus species, and Corynebacterium jeikeium, organisms that have become fairly common in cancer patients.

Anti-Infective Agents↗
PubMed1990

Medication compliance, antidepressant blood levels, and side effects in Southeast Asian patients.

A study of medication compliance, side effects, and clinical change with the use of antidepressants in 32 Southeast Asian refugee patients seen at an urban mental health center is reported. Patients met criteria for either major depressive episode, posttraumatic stress disorder, or both. Only five of the 32 patients who stated that they were taking their medications regularly had antidepressant blood levels in the therapeutic range. Another 10 patients had subtherapeutic levels and the remaining 17 had undetectable blood levels. Patients with therapeutic blood levels had fewer side effects (p = 0.049) than patients with undetectable blood levels. Blood levels tended (p = 0.070) to be correlated with clinical improvement. The authors discuss cultural attitudes of Southeast Asian refugee patients toward medication use and side effects that appear to influence medication compliance.

Adult↗
PubMed1989

A new approach to positron emission tomography.

A recently developed detection principle for gamma rays offers the prospect of improving the performance of positron emission tomographic scanners. This detection principle is based on the use of BaF2 scintillator and photosensitive wire chambers. We present technical results obtained with a prototype detector. It is shown that the impact point of the gamma ray can be determined with a precision of a few mm and that the detection efficiency is 60% with a time resolution of 10 ns (FWHM). A scanner based on the new principle is described and its anticipated performance discussed.

Tomography, Emission-Computed↗
PubMed1989

Depression and posttraumatic stress disorder in Southeast Asian refugees.

The authors report on 404 Southeast Asian refugees seen at a community clinic. Approximately three-quarters of these patients met DSM-III criteria for major depressive episode, and 14% had posttraumatic stress disorder. Complaints of pain and sleep disturbances were the predominant presenting symptoms. Most of the men were married, but more than 40% of the women were widowed. Between 15% and 30% of the patients reported specific traumatic experiences either in their homeland or during their escape. Widowhood and such traumatic experiences were positively correlated with more symptoms of depression and anxiety.

Acculturation↗
PubMed1988

Topical beta-blocker therapy and central nervous system side effects. A preliminary study comparing betaxolol and timolol.

Topical beta-blocking agents have been associated with adverse central nervous system (CNS) effects, including depression, emotional lability, and sexual dysfunction. Two studies were done to determine if patients who develop CNS effects while using timolol maleate would improve with betaxolol hydrochloride. In one study, 18 patients with CNS symptoms during timolol therapy were switched to betaxolol. Sixteen of the 18 patients noted symptomatic improvement with betaxolol. The second study involved seven patients with CNS symptoms during timolol therapy who were entered into a double-masked cross-over study. In two patients CNS symptoms resolved with betaxolol; in three patients symptoms improved; and in one patient symptoms worsened with betaxolol. Although factors influencing beta-blocker activity in the CNS are not well understood, there may be some advantage to a selective agent.

Administration, Topical↗
PubMed1988

Serum alpha fetoprotein in 714 mentally retarded carriers of hepatitis B surface antigen.

Sera from 714 mentally retarded carriers of hepatitis B surface antigen were screened for alpha fetoprotein (AFP) by monoclonal radioimmunoassay. Serum AFP levels were less than 20 mcg/L in 708 (99.2%) carriers. One 29-year-old carrier with normal liver function had serum AFP level of 1500 mcg/L, which increased to 12,500 mcg/L after 72 days. She died of multifocal hepatocellular carcinoma (HCC) with cirrhosis. Five other carriers with serum AFP levels between 20 and 165 mcg/L are alive without clinical HCC. No correlation was found between serum AFP level and race, age, sex, Down's syndrome, serum alanine aminotransferase level, and hepatitis B e antigen positivity. Single cross-sectional serum AFP screening by itself is not sufficient for early diagnosis of HCC.

Adolescent↗
PubMed1988

Hepatocellular carcinoma in hepatitis B surface antigen carriers in eight institutions.

We reviewed records of all persons dying between 1979 and 1986 in eight California institutions for the mentally retarded. Autopsies had been done in 71% of the 1,181 deaths. Nine deaths were due to hepatocellular carcinoma, which invariably developed in carriers of hepatitis B surface antigen (HBsAg) and was fatal within four months of diagnosis. The mean age at death was 32.7 years. The incidence of hepatocellular carcinoma in HBsAg carriers was 140 times greater than in the US population. Persistent hepatitis B infection was probably etiologically related to hepatocellular carcinoma in this population, which is relatively free of exposure to other hepatocarcinogens.

Adult↗
PubMed1988

Susceptibility status of Aedes albopictus to three topically applied adulticides.

The baseline susceptibility of Aedes albopictus (Sabah strain) to malathion was determined. Both laboratory-colonized and field-collected Ae. albopictus at Harris County, TX are resistant to malathion but susceptible to Scourge. The acute toxicity of bendiocarb to Ae. albopictus is confounded by its rapid knockdown and delayed recovery syndrome of poisoning.

Aedes↗
PubMed1988

Use of fetal cardiotocographic monitor in the evaluation of urinary incontinence.

Thirty-five women (mean age 52 years, mean parity 3) were evaluated consecutively for urinary incontinence. Stability of the bladder was evaluated by standing provocative water urethrocystometry, using a microtip pressure transducer and a multichannel electrophysiologic recorder. Cystometry was repeated immediately after emptying of the bladder. Second cystometry (standing provocative) was performed using a fetal cardiotocographic monitor for pressure recording. The simple cystometry (using the cardiotocograph technique) was very sensitive when evaluating women with a stable bladder (n = 25) and less sensitive when detecting bladder instability (n = 10). We conclude that the use of this simple technique is a viable option if urodynamic equipment is unavailable. There is no need for further evaluation in patients with findings of a stable bladder, but if bladder instability is detected, further in-depth evaluation is required.

Adult↗