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Biomedical subjects

J Yeh

Publications and source records attributed to J Yeh.

At least 109 records · Page 6Linked to original sources
PubMed1987

Capillary gas chromatographic-electron capture detection of coca-leaf-related impurities in illicit cocaine: 2,4-diphenylcyclobutane-1,3-dicarboxylic acids, 1,4-diphenylcyclobutane-2,3-dicarboxylic acids and their alkaloidal precursors, the truxillines.

A method has been developed that allows for the detection of the eleven stereoisomers of diphenylcyclobutanedicarboxylic acid in illicit cocaine samples, including alpha-, gamma-, and epsilon-truxillic acids and beta- and delta-truxinic acids. These, and other carboxylic acids, were also detected as ester moieties of alkaloidal impurities in illicit cocaine as well as in alkaloids of the South American coca leaf, e.g., alpha- and beta-truxilline. After lithium aluminum hydride reduction of the acidic and basic extracts of a prepared sample, the reduced species were derivatized with heptafluorobutyric anhydride in the presence of pyridine. The heptafluorobutyryl derivatives of the reduced diphenylcyclobutanedicarboxylic compounds were easily detected on-column at low picogram levels using a moderately polar fused-silica capillary column in the splitless mode and interfaced with a 63Ni electron-capture detector.

Alcohols↗
PubMed1987

Is maternal alkalosis harmful to the fetus?

Normal pregnancy is characterized by a compensated respiratory alkalosis. The effect of maternal alkalosis on the fetus is less well understood than the more common problem of maternal acidosis. We present a case of maternal alkalosis, complicated by bronchial asthma, in which the fetus was stillborn. The pathophysiology of this condition is discussed with data to support the potential harm of maternal alkalosis in pregnancies complicated by a fetus with borderline reserve. In such instances, the fetus should be carefully monitored and consideration might be given to therapy such as the use of acetozolomide, discouraging hyperventilation by the mother and even early delivery of the fetus.

Adult↗
PubMed1987

Artificial insemination with donor sperm: a review of 108 patients.

Artificial insemination with donor sperm (AID) has been a major form of treatment among infertile couples with defects in sperm production. In this report, we review our experience from 1980-1985. A total of 108 patients underwent AID, with 75 resultant pregnancies. Of patients achieving pregnancy, 47% became pregnant after the third cycle and 92% by the twelfth cycle. A higher success rate and/or smaller number of AID cycles were positively associated with patient age of 35 or less and negatively associated with endometriosis. This information is useful in counseling couples interested in pursuing AID.

Adult↗
PubMed1987

Serum osteocalcin and total body calcium in normal pre- and postmenopausal women and postmenopausal osteoporotic patients.

Serum osteocalcin was measured in 51 normal pre- and 114 postmenopausal women and in 41 postmenopausal osteoporotic patients. Total body calcium (TBCa) was determined in the same individuals by neutron activation analysis. Many of the perimenopausal nonosteoporotic women had increased serum osteocalcin values, but 15 yr or more after the menopause most of the women had serum osteocalcin levels in the normal range. Comparing normal women before and after menopause, the mean serum osteocalcin levels [7.8 +/- 4.7 (+/- SE) and 10.1 +/- 9.4 ng/mL] were not significantly different; however, the TBCa values (898 +/- 99 and 806 +/- 111 g) were significantly different (P less than 0.001). When the normal postmenopausal women were regrouped according to high vs. low osteocalcin values, TBCa and phosphorus content as well as forearm linear bone density were significantly lower in the high osteocalcin group, even though most of the other variables, including urinary hydroxyproline excretion, serum alkaline phosphatase, age, height, and weight, were not different. Osteoporotic women had a mean serum osteocalcin concentration of 17.4 +/- 8.6 ng/ml and a TBCa of 657 +/- 83 g, both significantly different from the respective values in normal and pre- and postmenopausal women (P less than 0.001 for both variables in comparison to each group). These data suggest that high serum osteocalcin levels, at least on a group basis, are an index of low skeletal mass.

Body Constitution↗
PubMed1987

The comparative pharmacokinetics of H1-receptor antagonists.

H1-receptor antagonists appear to be absorbed rapidly after oral administration, with peak serum concentrations being reached one to three hours after a dose. For most of these drugs, the absolute bioavailability is unknown because no intravenous formulations are available for comparative purposes. The serum elimination half-life values of these agents are variable: a few hours for terfenadine and triprolidine; about 9 hours for cetirizine, azatadine, and loratadine; from 20 to 25 hours for hydroxyzine, chlorpheniramine, and brompheniramine; and from 5 to 14 days for astemizole. Few pharmacokinetic studies of H1-receptor antagonists in children have been reported. However, it is known that chlorpheniramine, hydroxyzine, cetirizine, and terfenadine have shorter elimination half-life values in children than in adults. Regardless of the age of patients, for most of the H1-receptor antagonists the apparent volumes of distribution and total body clearances appear to be large (3.4 to 18.5 L/kg and 4.4 to 32.1 mL/min/kg, respectively). Cetirizine is an exception, with values of 0.8 L/kg and 0.5 mL/min/kg. Urinary excretion of unchanged antihistamine is higher after cetirizine (60% of dose) than any other H1 blocker. For H1-receptor antagonists with long half-life values, steady state may not be reached for several days (chlorpheniramine and brompheniramine) or several weeks (astemizole), and significant accumulation of drug occurs if the dosing interval is more frequent than every half-life. There is no evidence for the introduction of metabolism of H1-receptor antagonists, even after months of treatment.

Adult↗
PubMed1987

Pharmacokinetics of cetirizine in the elderly and patients with renal insufficiency.

The disposition of cetirizine, a new H1-receptor antagonist, was evaluated in 30 healthy adults of various ages and in 15 adults with various degrees of renal insufficiency. The purpose of the evaluation was to determine whether dosage schedules of cetirizine will require modification in the elderly or patients with renal insufficiency. We found that the elimination half-life of cetirizine was prolonged in patients with mild and moderate renal insufficiency, compared with age-matched individuals with normal renal function (19.0 +/- 3.3 and 20.9 +/- 4.4 hours, vs 7.4 +/- 3.0 hours, respectively). However, the mean apparent steady-state volume of distribution did not differ significantly between these subject groups (range 0.41 to 0.47 L/kg). Total body clearance and renal clearance of the drug were both significantly lower in the patients with renal insufficiency. In elderly subjects, the elimination half-life of cetirizine was significantly prolonged compared with younger adults, and apparent total body clearance was significantly reduced. Again, there was no significant difference in the volume of distribution between the groups. Linear regression showed good correlations between the disposition characteristics of cetirizine and age as well as creatinine clearance. However, we found no relationship between age and the ratio of apparent total body clearance of cetirizine to creatinine clearance. Thus the disposition of cetirizine is independent of age but dependent on renal function. The relationship between apparent total body clearance of cetirizine and creatinine clearance was significant only in patients with creatinine clearances greater than 40 mL/min. Progressive decrements in creatinine clearance were not associated with similar changes in the pharmacokinetic parameters of cetirizine.

Adult↗
PubMed1987

The metabolism and pharmacokinetics of 14C-cetirizine in humans.

This study investigated the metabolism and pharmacokinetics of cetirizine, a new H1-receptor antagonist. Single oral doses of 14C-cetirizine dihydrochloride (10 mg) in aqueous solution were administered to six healthy male volunteers. The drug was rapidly absorbed: The peak mean concentration of radioactivity (359 ng-equivalents/mL) and of unchanged drug (341 ng/mL) were achieved within one hour. Mean concentrations of cetirizine declined biexponentially and had a mean elimination half-life of 7.4 hours. The drug was excreted quite rapidly, with 60% of the dose recovered in the 24-hour urine. An additional 10% was excreted in urine over the next four days. Approximately 10% of the dose was excreted in feces over the five-day study period. The dose was excreted mainly as the unchanged drug. Examination of the radioactive compounds present in the plasma, and excreted in the urine and feces indicate that there is little metabolism of cetirizine. One minor metabolite, formed by oxidative O-dealkylation of the cetirizine side chain, was detected in plasma and feces.

Adult↗
PubMed1982

Effects of vitamins B1, B2, B6 and C on erythrocyte enzymes in South African Bantu.

Erythrocyte transketolase (ETK), glutathione reductase (EGR) and glutamate pyruvate transaminase (EGPT) enzyme activities and coenzyme effects (in vitro coenzyme stimulation) were studied in 30 random, 10 primary hepatoma, and 3 pellagrins natives from Mozambique. Twenty-nine subjects of the random group exhibited ETK coenzyme effects below 20%. Urinary thiamine levels in this group were in normal or high ranges. The primary hepatoma group had 4 with ETK coenzyme effects above 30%, and 3 of the 4 had low level urinary thiamine excretions. Of the three pellagra patients in the study, none showed biochemical vitamin B1 deficiency. All primary hepatoma and 23 random natives had EGR coenzyme effects above 30%, but the daily urinary riboflavin excretions correlated with the coenzyme effect in only the random group. EGPT activities were spread over a wide range. The random group with high EGPT activity showed a correlation with low coenzyme effect, while the primary hepatoma group did not exhibit this correlation. After 4-day single-vitamin treatment, vitamin B1 increased total ETK and vitamin B2 increased total EGR (after in vitro coenzyme saturation). Vitamin B6 did not increase total EGPT. Vitamin B2 was less effective on total EGR in primary hepatoma than in random subjects.

Alanine Transaminase↗
PubMed1979

Characterization of a retrovirus isolated from normal mink cells co-cultivated with a dog mammary tumour.

A retrovirus antigenically distinct from known type C, B and D viruses was isolated from normal mink (Mustela vison) lung cells that had been co-cultivated with 5-iododeoxyuridine- and dexamethasone-treated dog mammary tumour cells. Cytogenetic studies of the virus-releasing co-culture showed mitotic figures identical to the normal mink cell line (MvlLu) with the exception of a low frequency of cells with extensive chromosomal breakage and uncoiling. The new virus bands at a buoyant density of 1.16 g/ml, contains 60S RNA and a reverse transcriptase which prefers Mn2+ over Mg2+ for the synthesis of DNA. This enzyme utilizes poly(rA).oligo(dT) more efficiently than poly(dA).oligo(dT) and is also able to synthesize DNA copies from the endogenous RNA. Morphologically, it is a typical type C virus. Filtered virus readily infects mink, dog and other mammalian cells indicating the amphotropic nature of its cell growth requirement. Hybridization studies showed that normal mink DNA contains multiple copies of proviral sequences of this newly isolated virus. Serological analyses indicate that the mink endogenous virus contains in its core protein, in addition to the interspecies type-C determinant, an antigenic component related to one of the determinants found in the feline leukaemia virus p30 protein. This determinant is not present in the Rauscher leukaemia virus, RD114 virus or simian sarcoma virus.

Animals↗
PubMed1977

Comparative studies on EBV antigens by immunofluorescence and immunoperoxidase techniques.

Three groups of EBV antigens, VCA, MA and EA, were compared by the techniques of electron microscopic immunoperoxidase (IP) and immunofluorescence (IF). P3HR-1 and EBV superinfected Raji cells served as targets for labelled sera from patients with BL, NPC and IM or from healthy donors. 125I peroxidase-labelled antibodies were also prepared to determine, autoradiographically, the penetration of the complex into the cell system, and to monitor the incubation and washing procedures. The development of a gentle sedimentation technique proved critical in handling the fragile target cells. VCA and MA were readily identified and localized by both procedures without significant modification of the basic techniques. Indentification of early antigens by IP required modification of the fixation method to include a brief treatment in acetone. The diffuse early antigen (EAD) was found to be associated with cellular ribosomes.

Antigens, Viral↗
PubMed1973

Characterization of virus-specific RNAs from subacute sclerosing panencephalitis virus-infected CV-1 cells.

CV-1 cells infected with subacute sclerosing panencephalitis (SSPE) virus incorporated uridine-(3)H into at least four virus-specific RNA components in the presence of actinomycin D. The component sedimenting fastest had a sedimentation coefficient of 50s corresponding to a molecular weight of 6 x 10(6). The other three RNA components have sedimentation constants of 35s, 22s, and 18s corresponding to molecular weights of 2.5 x 10(6), 1.0 x 10(6), and 0.75 x 10(6), respectively. The base composition of the 50s RNA is distinct from that of cellular RNA and comparable with base compositions of viral RNAs of other paramyxoviruses. The base composition of the 18s RNA shows approximate complementarity with the 50s RNA. RNA-RNA annealing experiments using unlabeled 50s SSPE RNA with labeled 18s RNA from cells infected with SSPE virus or measles virus show 100% annealing with 18s SSPE RNA but only 60% annealing with 18s measles RNA. These experiments suggest some differences between the 18s RNAs of SSPE virus-infected cells and measles virus-infected cells.

Adenine↗
PubMed1972

The pi-histidine factor of Salmonella typhimurium: a demonstration that pi-histidine factor integrates into the chromosome.

The Salmonella typhimurium pi-histidine episome was identified by Ames et al. (2) in an unstable partial revertant of a deletion mutation-containing strain, hisG203. HisG203 lacks the histidine operator, promoter, and part of the first structural gene. In this paper, we study some properties of pi factor and demonstrate a low frequency of pi integration into the chromosome at or near the histidine region.

Acridines↗