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Biomedical subjects

F Liu

Publications and source records attributed to F Liu.

At least 739 records · Page 41Linked to original sources
PubMed1986

Serum somatomedin levels in adults with chronic renal failure: the importance of measuring insulin-like growth factor I (IGF-I) and IGF-II in acid-chromatographed uremic serum.

Somatomedin levels measured by radioreceptor assay (RRA) or RIA on acid-ethanol-extracted or unextracted serum from patients with uremia are quite variable relative to normal values. We have investigated whether compounds accumulating in uremic serum were interfering with these RRA and RIA measurements. Insulin-like growth factor I (IGF-I) and IGF-II were separated from carrier proteins by either Sephadex G-50 acid chromatography or acid-ethanol extraction. IGF-I was measured by RIA, and IGF-II was determined by rat placental membrane RRA. IGF-I levels in the acid-ethanol extracts of serum from eight uremic adults were only 50% of the levels found in seven normal subjects, and IGF-II levels in these uremic patients were 350% of normal values. However, these significant differences were not found when comparable serum samples were acid chromatographed rather than acid-ethanol extracted; instead, IGF-I levels were 343 +/- 168 (mean +/- SD) ng/ml in uremic patients and 325 +/- 54 ng/ml in normal subjects, while IGF-II levels were 780 +/- 215 ng/ml in uremic patients and 588 +/- 46 ng/ml in normal subjects. To determine whether compounds that interfere with somatomedin assays were present in the acid-ethanol extracts of uremic serum, we acid chromatographed these extracts and found that a compound eluting in the carrier protein fraction of the uremic extract artifactually decreased IGF-I levels measured by RIA and increased IGF-II levels measured by RRA. We also found that unsaturated carrier protein binding of IGF-I and IGF-II was significantly increased in the carrier protein fraction of uremic acid-ethanol extracts at the dilutions used for somatomedin assays. We conclude that acid chromatography of unextracted or acid-ethanol-extracted uremic serum is necessary to remove a compound, probably unsaturated carrier protein, which interferes with RIA of IGF-I and RRA of IGF-II. Once this compound is removed, serum IGF-I levels (RIA) in uremic patients are not different from normal, and serum IGF-II levels (RRA) are not lower than normal.

Adult↗
PubMed1985

The effect of partial gastrectomy on lipoproteins and other characteristics.

Among 6860 50-77 year old men of Japanese ancestry examined in Honolulu 291 were known to have had a gastrectomy for benign gastric (189) or duodenal (102) ulcer, and 132 had documented peptic ulcer disease treated medically. Total serum cholesterol averaged 12 mg% lower in the surgical group than in the general population (p less than 0.01) while the medically treated men had intermediate values. Fasting lipoprotein determinations done in a sub-sample showed that the lower total cholesterol in the surgical group was due to depressed LDL, while HDL was higher in the operated men than in either the general population or the medically treated patients (p less than 0.01). The surgical patients were heavier users of cigarettes, beer and coffee and averaged about 10 lb. lighter than either the medically treated patients or the rest of the population. However, in multivariate analysis these differences did not not account for the differences in lipoproteins. A small decrement in blood pressure in the surgical patients as compared to the rest of the population became non-significant when weight and others factors were taken into account.

Aged↗
PubMed1984

Gram stain in Legionnaires' disease.

A case of Legionnaires' disease is presented in which gram staining of impression smears from lung biopsy specimens showed Legionella pneumophila while other laboratory findings remained negative. This case illustrates the usefulness of gram staining in this disease and in the management of therapy.

Bacteriological Techniques↗
PubMed1984

Mycobacterium thermoresistibile infection in an immunocompromised host.

This is the second report of Mycobacterium thermoresistibile as the etiological agent of a pulmonary granuloma and the first occurrence of this organism in a patient who has not been outside the continental United States. The organism is susceptible to rifampin, ethambutol, and streptomycin but resistant to isoniazid and p-aminosalicylic acid.

Granuloma↗
PubMed1984

Somatomedins and insulin in diabetic pregnancies: effects on fetal macrosomia in the human and rhesus monkey.

The concentrations of the somatomedins (SMs) insulin-like growth factors I and II (SM-C/IGF-I and IGF-II) were measured by RIA in six normal and seven insulin-dependent diabetic pregnant women and their infants at delivery. SM-C/IGF-I and IGF-II levels in the two groups of women were similar. Maternal IGF-II concentrations correlated with maternal hemoglobin AIc levels (r = 0.68) and infant birth weight ratios (actual birth weight/expected 50th percentile sex-corrected birth weight for gestation age; r = 0.54). SMC/IGF-I and IGF-II levels in umbilical plasma in infants of diabetic mothers did not differ from those in control infants, but were lower than the corresponding maternal values. In contrast, umbilical plasma levels of C-peptide immunoreactivity were significantly elevated in the infants of diabetic mothers (2.25 +/- 1.85 (+/-SD) vs. 0.34 +/- 0.15 pmol/ml; P less than 0.01). The infant birth weight ratio was logarithmically correlated with the umbilical plasma C-peptide immunoreactivity (r = 0.78). SM levels were also measured by radioreceptor assay in five normal and five hyperinsulinemic rhesus monkey fetuses. When chronic hyperinsulinemia was produced by continuous SC infusion of insulin in the fetal rhesus monkey, the fetal birth weight ratio was also found to be logarithmically correlated with the fetal plasma insulin concentration (r = 0.81). The fetal SM peptide content was elevated only in the fetuses with plasma insulin levels greater than 3000 microU/ml. The fetal weight gains in response to hyperinsulinemia in the human and rhesus are similar. Since fetal SM levels in the humans and monkeys were not significantly different in the two groups, our data suggest that insulin plays the predominant role in stimulating human and subhuman primate excess fetal weight gain of the infant of the diabetic mother during the latter part of gestation.

Adult↗
PubMed1983

Levels of insulin-like growth factors I and II in human cord blood.

Levels of insulin-like growth factors I and II (IGF-I and IGF-II) and somatomedin peptide content (SMPC) were measured in 32 normal term and 11 preterm infants. After acid chromatography to remove somatomedin-binding protein, SMPC was measured by placental membrane radioreceptor assay, while plasma IGF-I and II concentrations were measured by specific RIAs. SMPC levels in term infants were significantly below normal adult levels [0.49 +/- 0.13 (+/- SD) U/ml for infants compared to 1.30 +/- 0.25 U/ml for adult males]. IGF-I levels in term infants were also low, averaging 113 +/- 35 ng/ml for infants; the normal adult levels is 184 +/- 32 ng/ml. The IGF-II level was 282 +/- 84 ng/ml for infants and 687 +/- 169 ng/ml for adults. Both IGF-I and II levels in preterm infants were lower than those in term infants. IGF-I, and IGF-II, and SMPC levels showed a positive correlation with birth weight in term infants. Both IGF-I and IGF-II levels showed a strong positive correlation with gestational age in all infants.

Adult↗
PubMed1982

Silica fragments from millet bran in mucosa surrounding oesophageal tumours in patients in northern China.

Millet bran is a component of the diet in the area of highest oesophageal cancer incidence in northern China. Millet bran was found to contain up to 20% by weight of silica; some of this silica occurs as friable sheets or sharply-pointed fibres. These types of silica in millet bran are the most likely source of an unusual contamination with fragments of silica found in the oesophageal mucosa surrounding tumours in patients in northern China. A group of mucosal samples analysed together contained over 5,000 particles/g (100 parts per million by weight), ten times as many as were found in tissue from normal controls taken at necropsy in London. The modal diameter was 10 microgram (1-70 microgram). The particles were in the body of the mucosa and were not simply a surface contaminant. Silica fragments and fibres of similar size originating from other plant species occur in the diet in the two other regions of greatest incidence of oesophageal cancer, the Transkei and Iran. If such fragments enter the mucosa, they must cause some degree of trauma, and they may also be able to stimulate proliferation by providing anchorage. These findings suggest the possibility that silica particles might be involved in the aetiology of oesophageal cancer.

Adult↗
PubMed1982

Serum lactate dehydrogenase isoenzyme 1 in patients with advanced testicular cancer.

Abnormal levels of serum lactic dehydrogenase-1 (LD-1) activity have been observed in 81% (34/42) of patients with stage III germ cell malignancy of the testis. The criteria for evaluation the electrophoretic isoenzyme patterns of these patients were, as follows: For criterion 1 elevations the LD-1 value in absolute units was greater than 52.0 U/I with the LD-1/Total LD ratio greater than 37.2%. Criterion 2 elevations had absolute values of LD-1 less than 52.0 U/I, but the LD-1/Total LD ratio was greater than 37.2%. For criterion 3 elevations of LD-1, the absolute value was greater than 52 U/I and the LD-1/Total LD ratio was less than 37.2% activity with the LD-5/LD-1 ratio less than 0.5; or when the LD-5/LD-1 ratio was greater than 0.5 but the LD-1 is equal to or greater than the LD-2. The frequency of LD-1 elevation correlated well with the extent of the disease (stage II-B-1 and 2, 50%; stage III-B-3, 86%; stage III-B-4, 91%; stage III-B-5, 93%). LD-1 elevation occurred in groups I, II, IV and V histopathologic cell types (Dixon and Moore Classification) and there did not appear to be any correlation between the histologic cell type and the frequency of elevation of LD-1. Interpretation of LD-1 activity only on the basis of its relative ratio to the total LD value (criterion 1 and 2) identified a total of 28 patients (67%). A criterion 3 elevation was demonstrated in 6 (14%) additional patients. All patients with persistent elevations or recurrent elevations of LD-1 have shown progressive or recurrent disease and patients with no clinical evidence of disease have demonstrated normal LD-1 values. In those patients with elevated LD-1 activity, serial measurements of serum. LD-1 isoenzyme reflect the response of the patient to therapy.

Choriocarcinoma↗
PubMed1982

Somatomedin peptide distribution and somatomedin-binding protein content in cord plasma: comparison to normal and hypopituitary plasma.

To characterize the macromolecular forms of somatomedin (SM) in human newborn plasma, we have studied the molecular weight distribution of endogenous SM peptides as well as the content and distribution of the acid-stable and the unsaturated SM-binding proteins (SMBP) in cord blood from 13 normal term infants. The radioreceptor assayable SM peptide content was significantly reduced in newborns compared with that in normal adults. Furthermore, 50% of the SM content of newborns circulated as part of a 50,000 mol wt complex, in contrast to adult plasma where the majority of SM peptide content is found in the 150,000 mol wt range. Unsaturated SMBP was strikingly elevated in newborns (mean +/- SRM, 2.75 +/- 1.73 U/ml) compared to adult values of 0.63 +/- 0.24. Sephacryl-200 chromatography demonstrated that the unsaturated SMBP is found in the 40,000-50,000 mol wt region in newborns, adults, and GH-deficient children, although adults appear to have a secondary peak of unsaturated SMBP in the 150,000 mol wt region. Assay of the acid-stable SMBP indicated similar levels in newborns (1.15 +/- 0.26 U/ml) and adults (1.18 +/- 0.47) and strikingly lower values in GH-deficient subjects. The molecular weight of the acid-stable SMBP of newborns, adults, and hypopituitary dwarfs appeared to be similar, measuring approximately 60,000. We conclude that despite low levels of SM peptides, human cord plasma contains normal levels of the acid-stable SMBP and elevated of the unsaturated SMBP. The role of these binding proteins in cord plasma remains uncertain, but suggests that other SM peptides may be important in fetal growth.

Adult↗
PubMed1982

A radioimmunoassay for insulin-like growth factor II specific for the C-peptide region.

Insulin-like growth factor II (IGF-II) is a human plasma peptide whose sequence is homologous to both insulin-like growth factor I/somatomedin C (IGF-I/SM-C) and human proinsulin in the A and B regions. However, there is no obvious homology in the C (connecting peptide) region. The synthetic 8-amino acid C-peptide segment of IGF-II (Ser-Arg-Val-Ser-Arg-Arg-Ser-Arg) was covalently linked to thyroglobulin to render it more antigenic. Antiserum against the IGF-II C-peptide was generated which had a titer of 1:2000 determined with [125I]IGF-II C-peptide. Half-maximum displacement was by 350 pg/ml IGF-II C-peptide or 80 ng/ml IGF-II. There was no displacement by IGF-I/SM-C, insulin, or a wide variety of peptides. There was also a high degree of species specificity of this antisera. Isoelectric focusing studies of immunoreactive IGF-II showed an apparent pI of 6-6.5. The mean (+/- SEM) level of IGF-II after acid chromatography of 28 normal adult males was 687.0 +/- 31.9 ng/ml. The mean of 8 acromegalics was 600.5 +/- 57.4 ng/ml, indistinguishable from normal. The IGF-II levels of 21 hypopituitary children were significantly lower (231.5 +/- 32.3 ng/ml). Thus, GH action appears to be necessary for normal levels of IGF-II, but excess GH does not cause an elevation above normal of IGF-II, unlike what is seen with IGF-I/SM-C. These structurally related IGF peptides have different control mechanisms and ultimately may play different functional roles. The availability of specific RIAs for the measurement of IGF-II will help to clarify its role in human physiology and disease states.

Acromegaly↗