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Biomedical subjects

K C Young

Publications and source records attributed to K C Young.

At least 55 records · Page 3Linked to original sources
PubMed1993

Detection of hepatitis C virus RNA in peripheral blood mononuclear cells and in saliva.

The nested polymerase chain reaction (PCR) technique was applied to investigate hepatitis C virus (HCV) RNA in the peripheral blood mononuclear cells (PBMCs), saliva, and serum of patients with chronic type C hepatitis. The specificity of the amplified products was analyzed and confirmed by agarose gel electrophoresis, Southern blot hybridization, and restriction endonuclease pattern analysis. HCV RNA was detectable in the PBMCs of 24% (12/50) of the patients. The HCV RNA detected in PBMCs was not due to the contamination from plasma, since no viral sequences could be detected in the third washing of PBMCs. Of the 12 patients with HCV RNA in PBMCs, five were negative for HCV RNA sequences in the serum. Thus the presence of HCV RNA in PBMCs was not strictly correlated to the results for sera. Among 25 patients with HCV RNA in their saliva, 18 were negative for PBMCs. Among 25 patients without HCV RNA in their saliva, five had HCV RNA in PBMCs. In conclusion, PBMCs are an extrahepatic target for chronic HCV infection. However, we do not suggest that PBMCs act as a vehicle for carrying HCV to saliva, since the presence of HCV RNA in PBMCs and in saliva was not closely correlated.

Base Sequence↗
PubMed1992

Detection of HCV RNA in saliva, urine, seminal fluid, and ascites.

Approximately half of the patients with type C hepatitis do not have a history of parenteral exposure. The route of nonparenteral infection remains unknown. To evaluate the possible role of body fluids, the existence of hepatitis C virus (HCV) RNA in saliva, urine, seminal fluid, and ascites was examined by "nested" polymerase chain reaction (PCR). Amplification of the HCV 5' noncoding sequences was carried out. The amplified product was confirmed by Southern blot hybridization and restriction endonuclease digestion. Among 34 patients with chronic liver disease who were positive for anti-HCV and serum HCV RNA, the prevalence of HCV RNA in body fluids was 100% (7/7) in ascites, 48% (15/31) in saliva, 24% (4/17) in seminal fluid, and 7% (2/29) in urine. The body fluids collected from 3 healthy subjects and 5 patients with chronic liver disease who were positive for anti-HCV but negative for serum HCV RNA were all negative for HCV RNA. Hence, the potential infectivity of body fluids in patients testing negative for serum HCV RNA can probably be discounted. Conversely, the presence of HCV RNA in saliva and seminal fluid of patients positive for serum HCV RNA suggests sexual and household contact as likely modes of nonparenteral transmission of type C hepatitis. Furthermore, the high prevalence of HCV RNA in ascites and saliva may have important implications in medical and dental practice.

Ascitic Fluid↗
PubMed1992

Analysis of peripheral blood of pregnant women for the presence of fetal Y chromosome-specific ZFY gene deoxyribonucleic acid sequences.

Deoxyribonucleic acid sequences of human ZFY (zinc-finger-Y) gene, a Y-chromosome-specific gene and candidate for the testis-determining factor, has been identified by an in vitro enzymatic deoxyribonucleic acid amplification method in peripheral blood specimens of women pregnant with male fetuses. This technique permits detection of ZFY gene deoxyribonucleic acid sequences in as few as a single male cell among 1,000,000 female cells. Maternal blood results were confirmed by amplification of ZFY gene deoxyribonucleic acid sequences in chorionic villus cells and by karyotyping in 33 of 36 pregnant women. There was no false-positive male result, and two of the three blood specimens with false-negative results were obtained from pregnant women at a very early gestational age. With properly designed guidelines, this deoxyribonucleic acid amplification method may be an alternative to determine the fetal sex for those pregnancies at risk for X-linked genetic disorders.

Base Sequence↗
PubMed1990

Reproducibility and action levels for gamma camera uniformity.

Deciding on the action level for gamma camera non-uniformity is difficult because the reproducibilities of quality control measurements and service adjustments are usually unknown. This work evaluated the reproducibilities of integral uniformity (IU), differential uniformity (DU) and the corrected relative standard deviation (CRSD). The latter was calculated by removing from the relative standard deviation of the pixel counts the component due to statistical fluctuations. The reproducibility of each parameter was evaluated by analysing 10 intrinsic flood acquisitions with total counts of 2, 5, 10 and 30 million. All three parameters were less reproducible at the lower count densities, but as expected IU and DU also showed higher mean values. CRSD was consistent and highly reproducible, at all count densities. At 10 million counts CRSD had a coefficient of variation (COV) of 1.3% which was a five-fold improvement over the 6.6% and 6.1% found for IU and DU, respectively. The relative sensitivity of IU, DU and CRSD was compared in monthly measurements on 10 gamma cameras over one year. No significant difference in relative sensitivity was demonstrated: a change in camera performance produced about the same percentage change in each parameter. The precision with which service engineers adjust gamma cameras was also assessed by measuring the uniformity of 10 gamma cameras immediately after service adjustment at monthly intervals over one year. Finally, general action levels were defined for IU, DU and CRSD at 7%, 5% and 2.5% respectively.

Gamma Cameras↗
PubMed1989

Detection of human papillomaviruses in exfoliated cervicovaginal cells by in situ DNA hybridization analysis.

A total of 851 specimens of exfoliated cervicovaginal cells and 27 specimens of male urethral smears obtained from 706 individuals with various clinical findings were examined for the presence of human papillomavirus (HPV) types 6, 11, 16, 18, 31, and 33 by in situ DNA hybridization analysis. The nonradioactive DNA in situ hybridization method used in this study showed no detectable cross-hybridization either among different types of HPV (except between types 6 and 11) or between HPV DNA and human cellular DNA. Furthermore, this system was found to be more sensitive than the Southern blotting method in detecting HPV. HPV was found in 233 of 276 (84.4%) and in 34 of 47 (72.3%) samples of cervicovaginal cells from patients with urogenital condylomata and cervical dysplasia, respectively. HPV was also detected in 6 of 39 (15.4%) women with normal cytological findings who were also symptom-free. Young women who were at low risk but were infected with HPV showed significantly reduced ratios of helper-inducer T lymphocytes to suppressor-cytotoxic T lymphocytes compared with those of uninfected normal controls (1.28 +/- 0.31 versus 2.47 +/- 0.64; P less than 0.001). This in situ DNA hybridization method can have broad application to the screening of HPV in early lesions and in normal-looking tissues and may be used to identify patients at risk of more serious or possibly malignant progression.

Blotting, Southern↗
PubMed1980

Studies on the setting behaviour of sealants using a new acoustic method of determining set.

An acoustic method has been used to compare the setting behaviours of three chemical and three u.v. activated sealants. The setting rates of the u.v. sealants were found to have similar sub-linear dependences on the applied u.v. intensity. However, considerable differences in the rates of set of these materials were noted when the same u.v. intensities were applied. Adjusting the composition of one of the sealants (Alphaseal) increased the penetration of the u.v. radiation, resulting in a ten-fold improvement in the setting rate. Suitable exposure times and the intensities of radiation necessary to satisfactorily set these u.v. sealants are recommended.

Acoustics↗
PubMed1980

Nuclear angiography in convalescent phase of myocardial infarction. Serial study of left ventricular performance.

Electrocardiograph-gated blood pool scans (anteroposterior and left anterior oblique projections) were recorded in 30 patients seven to 10 days after myocardial infarction. Left ventricular ejection fractions (mean 0.26 +/- 0.10) were lower on average than values previously obtained in 11 normal subjects (mean 0.52 +/- 0.06) and correlated broadly with the clinical assessment of left ventricular performance. Ejection fractions were lower in anterior (mean 0.21 +/- 0.09) than inferior (mean 0.32 +/- 0.08) infarcts. Abnormal wall motion was detected in 11 of 15 anterior infarcts and in six of 13 inferior infarcts: mean ejection fractions associated with global asynergy, segmental asynergy, and normal wall motion were 0.15, 0.26, and 0.36, respectively. Twenty-four patients were reinvestigated two months later. Though there was some change in the clinical status of eight patients, wall motion and ejection fraction were unchanged (mean difference -0.005 +/- 0.036). Twelve patients were reinvestigated six months after infarction. The ejection fraction for the group was significantly lower than the values obtained at 10 days and two months, and four individual changes were significant when compared with the first study. Changes in wall motion were observed in one patient. From this radionuclide study, we conclude that ejection fraction and wall motion do not improve after the early convalescent phase of myocardial infarction.

Adult↗
PubMed1978

Microhardness studies on the setting characteristics of fissure sealants.

The hardness of five fissure sealants was measured using a Wallace Microhardness Tester and found to continue to increase long after the initial setting. The effect of the intensity of radiation and exposure time on the setting of two u.v. activated sealants (Nuva-seal and Alphaseal) was also investigated, with higher intensities producing both a more rapid set and greater final hardness. Alphaseal required longer exposure at a given intensity of u.v. radiation to achieve the same hardness as Nuva-seal, and displayed relatively slow setting in depth, which could give rise to incomplete polymerization during clinical use, resulting in early sealant loss. Thus special care must be taken to ensure that Alphaseal receives an adequate exposure to u.v. radiation, and sources which are suitable for setting Nuva-seal may not be sufficiently powerful when applying Alphaseal.

Acrylates↗
PubMed1978

Ultra-violet absorption by two ultra-violet activated sealants.

Since the ability of u.v. setting pit and fissure sealants to set in depth is dependent on the penetration of the u.v. radiation, the absorption coefficients of Nuva-seal and Alphaseal were determined at 365 nm, the wavelength of radiation used to polymerise both materials. Nuva-seal and Alphaseal had absorption coefficients of 0.165 mm-1 and 6.25 mm-1, respectively. The u.v. fluorescent dye present in Alphaseal contributed 2.5 mm-1 to its absorption coefficient and the remaining absorption was due to the 5% w/w catalyst concentration present, since the basic resin had no significant absorption. Therefore Nuva-seal may set adequately to the depths required of fissure sealants, but Alphaseal may not, unless a very high intensity u.v. source is used. A reduction in the catalyst concentration and the removal of the u.v. fluorescent dye might improve the setting characteristics of Alphaseal.

Adsorption↗
PubMed1977

The performance of ultraviolet lights used to polymerize fissure sealants.

The performances of ultraviolet (uv) lights used to initiate polymerization in fissure sealant systems were studied with a view to establishing recommendations for improving clinical results. The relationship between the setting time of an uv polymerized sealant (Nuva-seal) and the intensity of radiation applied was first established. This was compared with the intensity and distribution of radiation from seven Nuva-lites and one Quartzlite. It was found that some of the Nuva-lites did not produce an average intensity of uv radiation sufficient to completely polymerize Nuva-seal within the manufacturer's recommended exposure times. It is suggested that this may be a factor contributing to the large variation in sealant retention found in the different clinical trials with Nuva-seal. Finally, a number of recommendations are made to ensure that sufficient uv radiation is applied to all sealant surfaces when the Nuva-seal system is used.

Dental Equipment↗
PubMedDate not supplied

The effect of the acute administration of tolbutamide on left ventricular function in insulin-dependent diabetics.

Despite better control of diabetic patients with morbidity and mortality from heart disease is significantly higher than in non-diabetics. While this may be a result of premature atherosclerosis or primary diabetic cardiopathy, the possibility of oral hypoglycemic agents have adverse cardiac effects must be considered. Using nuclear angiography the effect of the acute administration of 1 g tolbutamide on left ventricular ejection fraction (EF) in a group of 10 Type-1 diabetics was investigated. There was no difference in the response of the EF when compared to the response in 10 diabetic controls given i.v. saline. While i.v. tolbutamide may have adverse cardiac effects when administered to animals or in vitro this does not necessarily apply to human diabetics.

Adult↗