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Biomedical subjects

S Ng

Publications and source records attributed to S Ng.

At least 73 records · Page 4Linked to original sources
PubMed1989

Obesity and breast disease. The role of the female sex hormones.

An Australian study of 513 women evaluated associations between obesity and both benign and malignant breast disease, and in particular investigated the role of female sex hormones. Women who gained more than 10 kg from early womanhood had a two-fold increase in risk of developing breast cancer, whereas lean women had a greater risk of being treated for benign breast disease. Obese women with breast cancer were more likely to have Stage II tumors but there was no significant association between obesity and tumor size or estrogen and progesterone receptor status. Obesity was strongly associated with the proportions of nonprotein-bound and albumin-bound estradiol, and inversely associated with sex hormone binding globulin (SHBG) levels and the proportion of SHBG-bound estradiol. In addition, age at menarche was inversely associated, and age at menopause directly associated with recalled weight at those time periods. These data demonstrate weight gain as a risk factor for breast cancer, and suggest a possible mechanism supporting its development.

Adolescent↗
PubMed1989

Genetic analysis of eight loci tightly linked to neurofibromatosis 1.

The genetic locus for neurofibromatosis 1 (NF1) has recently been mapped to the pericentromeric region of chromosome 17. We have genotyped eight previously identified RFLP probes on 50 NF1 families to determine the placement of the NF1 locus relative to the RFLP loci. Thirty-eight recombination events in the pericentromeric region were identified, eight involving crossovers between NF1 and loci on either chromosomal arm. Multipoint linkage analysis resulted in the unique placement of six loci at odds greater than 100:1 in the order of pter-A10-41-EW301-NF1-EW207-CRI-L581-CRI-L946 -qter. Owing to insufficient crossovers, three loci--D17Z1, EW206, and EW203--could not be uniquely localized. In this region female recombination rates were significantly higher than those of males. These data were part of a joint study aimed at the localization of both NF1 and tightly linked pericentromeric markers for chromosome 17.

Chromosome Mapping↗
PubMed1987

Linkage studies with chromosome 17 DNA markers in 45 neurofibromatosis 1 families.

A locus for von Recklinghausen neurofibromatosis (NF1) has recently been mapped near the chromosome 17 centromere. We have extended these linkage studies by genotyping 45 NF1 families with three DNA probes known to be linked to the chromosome 17 centromeric region. Of 34 families informative for NF1 and at least one of the three probes, 28 families show no recombinants with the disease gene. These data provide additional support for genetic homogeneity of NF1 and for a primary NF1 locus linked to the chromosome 17 centromere. Among the informative families were 7 families with apparent new NF1 mutations. Our data suggest that these mutations are probably at the chromosome 17 NF1 locus.

Chromosomes, Human, Pair 17↗
PubMed1986

Hercon technology for transdermal delivery of drugs.

The Hercon controlled drug delivery technology is based on a multi-layered laminated polymeric structure, in which a layer of vinyl chloride copolymer or terpolymer containing the drug is sandwiched between two or more layers of polymeric films. The drug is released from the device at a controlled rate by a process of diffusion through the reservoir and one of the outer layers, which can function as a rate controlling membrane. This basic technology has been successfully utilized for the development and commercialization of Nitroglycerin Transdermal System (NTS, Bolar Pharmaceutical Co., Inc). In vitro and in vivo investigations of transdermal delivery of different other drugs from the Hercon polymeric devices have indicated the feasibility of using this system to meet a variety of therapeutic needs.

Administration, Cutaneous↗
PubMed1985

Prolonged outbreak of Norwalk gastroenteritis in an isolated guest house.

During November and December 1982, a persistent outbreak of gastroenteritis took place in an isolated guest house. An estimated 26% of the changing population of guests and staff developed symptoms. Laboratory studies implicated Norwalk agent as the cause of illness, although the original source of the outbreak could not be established. Information on clinical features of the illness, its mode of spread, and eventual control is presented.

Adolescent↗
PubMed1985

Neurological soft signs. Their relationship to psychiatric disorder and intelligence in childhood and adolescence.

Sixty-three male and 27 female adolescents known to have had neurological soft signs at the age of 7 years were compared with controls with no soft signs at age 7. Adolescents with early soft signs had significantly lower IQs and were more likely to have a psychiatric disorder characterized by anxiety, withdrawal, and depression. All the girls and 80% (12/15) of the boys with an anxiety-withdrawal diagnosis showed early soft signs. There was no relationship between early soft signs and attention deficit or conduct disorders. Examination of the relative contributions of anxiety at age 7, IQ, and social and family disadvantage to later diagnosis showed that most of the variance was accounted for by soft signs independently of IQ. Soft signs and anxious dependent behavior at age 7 were strongly predictive of persistent psychiatric disorder characterized by anxiety and withdrawal.

Adolescent↗
PubMed1984

A pre-set ultraviolet dose meter.

The design, construction and performance of an ultraviolet radiation (UVR) pre-set dose meter is described. The meter simultaneously displays irradiance, dose, and elapsed time, and incorporates a calibrated variable gain control to permit use with detectors of varying sensitivity. The meter has been developed to permit the automatic administration of UVR dose in photosensitivity testing. The UVR is generated by a Xenon lamp and delivered to the patient via a monochromator and liquid filled light guide. A beam-splitter in the light guide applicator diverts a small fraction (9%) of the UVR onto a photo-diode detector connected to the meter. When the dose recorded by the meter reaches the pre-set value the meter activates a solenoid which closes the monochromator exit slit shutter. This on-line control of the dose ensures that any fluctuations in irradiance are compensated so that the pre-set test dose is always administered to within the 1% accuracy of the instrument.

Humans↗
PubMed1980

Blood pressure in the first 6 weeks of life.

Systolic blood pressure was measured at frequent intervals during the first 6 weeks of life in 99 normal neonates. Blood pressure rose from a mean of 70 mmHg at age 2 days, to 93 mmHg at age 6 weeks in babies awake; the majority of this rise (14 mmHg) took place in the first 2 weeks of life. The blood pressure measured when infants were asleep was lower than in those awake, but increased in a similar manner. Blood pressure of infants at 2 days was not significantly affected by method of delivery, or by the anaesthesia or analgesia that the mothers received in labour. It was not related to the Apgar score at one or five minutes.

Apgar Score↗
PubMed1979

The irreversible binding of benzo[a]pyrene to rat liver macromolecules in vivo and in vitro: effects of agents that influence benzo[a]pyrene metabolism.

The present study was carried out to determine the effects of agents that influence benzo[a]pyrene (BP) metabolism in vitro on the irreversible binding of BP to rat hepatic macromolecules in vivo. The irreversible binding of [3H]BP was found to be both dose and time dependent after its intraperitoneal administration to male Wistar rats. The SKF 525-A, at doses of 50 and 75 mg/kg, ip 3 h before BP, decreased the level of binding from control by 31 and 34%, respectively. At 35 mg/kg, SKF-525-A had no effect. Diethyl maleate (0.6 mL/kg, ip) and cysteine (150 mg/kg, ip), 30 and 5 min before BP, respectively, did not alter the binding of BP from control. Oral methadone treatment, previously shown to increase selectively epoxide hydrase activity in male Wistar rats, also failed to alter the amount of BP bound to hepatic macromolecules. 3-Methylcholanthrene (20 mg/kg per day, ip, for 2 days) administered 24 h before BP, decreased the level of binding from control by 30%. Parallel in vitro studies were carried out with the various agents used in vivo.

Animals↗
PubMed1977

Effect of specific trifluoroacetylation of individual cytochrome c lysines on the reaction with cytochrome oxidase.

We have prepared three different cytochrome c derivatives, each containing a single specifically trifluoroacetylated lysine at residues 13, 55, and 99, respectively. The only modification that affected cytochrome c oxidase (EC 1.9.3.1) activity was that of lysine-13 at the top of the heme crevice. Trifluoroacetylation of lysine-13 increased the apparent Michaelis constant fivefold compared to that of native cytochrome c, but did not affect the maximum velocity. Trifluoroacetylation of lysine-55 at the left side of the cytochrome c molecule did not affect cytochrome oxidase activity in any way, nor did trifluoroacetylation of lysine-99 at the rear of the cytochrome c molecule. This indicates that the cytochrome oxidase binding site on cytochrome c involved only the front of the cytochrome c molecule and those lysines immediately surrounding the heme crevice.

Animals↗
PubMed1975

Effect of chromosomal proteins extractable with low concentrations of NaCl on chromatin structure of resting and proliferating cells.

When quiescent WI-38 cells are stimulated to proliferate by nutritional changes, the chromatin of stimulated cells shows an increased ellipticity in circular dichroism spectra and an increased ability to bind ethidium bromide. The differences between the chromatins of quiescent and stimulated cells are abolished if both chromatins are treated with 0.25 M NaCl. However, when salt-treated chromatins are reconstituted by dialysis agains 10 mM Tris-HCl, the difference in circular dichroism spectra and ethidium bromide binding re-appear. Furthermore, addition of the 0.25 M NaCl extract from chromatin of stimulated cells to chromatin of quiescent cells causes an increased ellipticity in circular dichroism spectra similar to that of stimulated chromatin. Since only proteins (mostly nonhistones) are detectable in the 0.25 M NaCl extract, these results strongly suggest that the chromosomal proteins extractable with low concentrations of salt are responsible for the functional and structural changes occurring in chromatin of WI-38 cells stimulated to proliferate.

Binding Sites↗
PubMed1975

Atomic absorption spectrophotometric determination of selenium in animal feed premix, using the vapor generation technique.

An atomic absorption spectrophotometric method, using the vapor generation technique for the determination of selenium in animal feed premixes containing 0.4-0.002% selenium, is described. After the sample was digested in perchloric acid and hydrogen peroxide and reduced with 6M HCl, 3 aliquots of sample, each containing about 0.4 mug Se, were taken for analysis by the standard addition method. Sodium borohydride pellets were used for the generation of selenium hydride. The relative standard deviation of a single determination averaged +/- 19%.

Animal Feed↗