Biomedical subjects
Publications and source records attributed to H J Lin.
Copper deficiency is reported in an infant of very low birthweight. It was characterised by extensive bone changes, severe neutropenia, and hypocupraemia. These manifestations could have been missed but for an intercurrent pneumonia which led to an x-ray of the chest.
In the course of evaluating various porous materials as candidates for prosthetic devices, a commercial stainless steel (316L) was found which was designed for porous filtration applications. Small bars (approximately to 3mm x 3mm x 20mm) were implanted in dog extremeties for periods of 10 to 15 weeks. The average tensile strength of the bone/(bone/metal) interface was found to be 0.975 kgf/mm2 (1380 psi) with no indication of variation with time of implantation. Scanning electron microscopy (SEM) combined with X-ray energy dispersive (XRED) analysis indicates production of calcified bone in the bone/metal composite. Inherent strength and porosity characteristic combined with biocompatbility indicate that this commercially available meterial is a viable implant candidate for attachment to the skeletal system.
An average tensile strength of 1.35 kgf/mm2 (1920 psi) was obtained. Comparison of all results with related studies on metallic and ceramic implants indicates the overall superiority of plastics as porous implants for many applications.
A prospective double-blind controlled study was performed on the effects of isoprinosine in 81 patients with clinical and histological features of classical acute viral hepatitis. Appetite was assessed daily. Serum alanine aminotransferase, aspartic aminotransferase, and bilirubin levels were assessed weekly. Changes in biochemical parameters, number of deaths, number of patients showing rise of aminotransferase levels despite treatment, and duration required for appetite to return to normal in each group were compared. Observation was continued for 4 weeks. Contrary to preliminary reports, no therapeutic benefit was demonstrated in any of these parameters. We concluded that isoprinosine was ineffective in the acute phase of classical acute viral hepatitis.
The direct comparison of O-alkylglycerol composition in the neutral lipids fractions prepared from human hepatocellular carcinomas with that in corresponding preparations from nonneoplastic liver is reported. Tumor-bearing liver and noncancerous liver specimens were obtained either during surgery or at autopsy. Thirty different tissue specimens obtained from 18 cases were analyzed. Representative samples from each specimen were examined microscopically to confirm the pathological diagnosis. Gas chromatographic analysis of alkylglycerol derivatives showed that hexadecylglycerol, octadecylglycerol, and octadecenylglycerol were the principal components. Compared to the noncancerous liver, hepatocellular carcinomas contained higher proportions of hexadecylglycerol and lower proportions of both C18-glyceryl ethers. Associated with this change was an increase in the proportion of saturated to monoenic alkylglycerols. These abnormalities appeared to be more severe in the necrotic areas of the tumors. Higher concentrations of neutral alkyl glycerolipids and of cholesterol were found in the tumors; no differences between the two groups could be found in the levels of ether-linked phosphoglycerides, triglycerides, and lipid phosphorus.
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A comparison of human adult and fetal adrenals with respect to their levels of glyceryl ether lipids and other lipid components is reported. Fetal glands contained significantly lower levels of alk-1-enyl phosphoglycerides and of cholesterol. Neutral glyceryl ether diesters, and ethanolamine and choline phosphoglycerides were isolated from adult adrenal tissue. The composition of the O-alkyl glycerol groups in these lipid fractions was obtained by means of gas chromatography of the trimethylsilyl ethers and diacetyl derivatives; O-alk-1-enyl glycerols were analyzed as their diacetates. About one-half of the alkyl and alk-1-enyl glycerol moieties present in glyceryl ether diesters contained hydrocarbon side chains with 20, 22, or 24 carbon atoms. Long hydrocarbon chains (C19-24) were also found in the O-alkyl glycerol moieties present in the total lipids of fetal adrenals.
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Thirty-nine children from three to 16 years of age were included in this study. Nineteen were diabetics, seven were "suspected" diabetics (with evidence of glucose intolerance but without repeated fasting hyperglycemia), and 13 were controls. Mean glucose disappearance rates (K) during intravenous glucose tolerance tests (IVGTTs) were 2.19 for the controls, 1.23 for the suspected diabetics, and 0.70 for 14 diabetics tested; the differences were statistically significant. Diabetics had the smallest and suspected diabetics the greatest plasma insulin responses during IVGTTs. Fasting plasma growth hormone (GH) varied widely. GH generally decreased or remained unchanged during IVGTTs, but two diabetics exhibited slight increases and two sustpected diabetics pronounced increases. Basement-membrane thickness (BMT) was examined in 42 quadriceps femoris needle biopsies. Average BMT (ABMT) and minimum BMT (MBMT) correlated well (r = 0.91). BMT did not correlate well with age or, in the diabetics, with duration of clinical disease. Diabetics had the greatest and controls the least mean ABMT and MBMT, but the differences were not statistically significant. High values (those exceeding mean control values by more than two standard deviations) were much more common among the suspected diabetics and the diabetics. One of 13 controls, three of six suspected diabetics, and six of 19 diabetics had high ABMT values; two suspected diabetics and five diabetics had high MBMT values. Correlations between BMT and K were negative for the most part, but correlation coefficients were small. Serial studies in four of the children suggest that BMT and glucose tolerance tend to change in opposite directions.
Longitudinal biochemical and histologic studies were carried out in 11 children receiving oral hypoglycemic agents. There were five "suspected" diabetics (with evidence of glucose intolerance but without repeated fasting hyperglycemia) and six diabetics. Mean fasting plasma glucose (FPG) values showed no significant change during treatment with phenformin alone. The mean FPG decreased significantly within six to 10 weeks after addition of tolazamide to the regimen, but the decrease was not sustained during long-term observation (seven months to four years). Glucose disappearance rate (K) generally increased as FPG decreased, but the number of observations was smaller, and mean values showed no significant change. Mean values for fasting plasma insulin and for peak insulin response to intravenously administered glucose did not change significantly. Changes in capillary basement membrane thickness (BMT) were found to be statistically significant in a number of individual instances. Decreasing BMTs were associated with increasing Ks and vice versa. A similar trend was apparent among other patients, in whom individual changes in BMT were not statistically significant. The pooled data were therefore subjected to chi-square analysis; K and average BMT were found to change in opposite directions (P less than 0.001); a similar relationship held for K and minimum BMT (P less than 0.05). But K and BMT did not correlate well as regards magnitude of change. Influences of phenformin and tolazamide on these changes could not be evaluated. Both BMT and K may be influenced by many complex variables, but the present findings indicate that glucose tolerance and BMT have a close interdependence.
We have shown that ether-linked glycerolipids accumulated in the adrenal, liver, and spleen of a male Chinese infant with Wolman's disease; the increases were mainly in the alkyl and alk-1-enyl glycerolipids that did not contain phosphorus. Alkyldiacylglycerol accounted for a portion of the rise in the neutral alkylglycerols. The spleen also contained increased amounts of ether-linked phosphoglycerides of the alkyl and alk-1-enyl types. Organs from a Niemann-Pick patient were also included in this study; they did not show comparable rises in the content of ether-linked glycerolipids, suggesting the possibility that storage of these compounds may be characteristic of Wolman's disease, or a variant form thereof.
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Hybridization of heterologous nucleic acids has provided the means for isolating a repeating sequence which is located next to template regions of DNA. Separated single strands of 32P-labelled DNA from Escherichia coli were to a limited extent able to anneal with DNA of Micrococcus lysodeikticus immobilized on nitrocellulose membrane filters. The resulting hybrid was resistant to enzymes specific for unpaired strands, nuclease S1 (Aspergillus oryzae) and exonuclease I (E. coli). The E. coli DNA so hybridized was isolated and characterized. It contained all four bases with cytosine predominating; strand length was about 50-60 nucleotides. Since these units occupied about 1-2% of the length of the E. coli chromosome, they would have to be repeated about 2000 times in a single cell. Formation of the unusual hybrid was not diminished by prior saturation of the E. coli DNA with homologous 3H-labelled RNA. In fact both RNA and additional increments of DNA were detected on the filters approximately in a 1:1 ratio, showing that some of the repeating sequences were physically continuous with transcribed regions of DNA.
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