Acid In Subjects Research Articles

This month in J Lab Clin Med: Issue highlights for February 2002

This month in J Lab Clin Med: Issue highlights for February 2002

Conversion of 7α-hydroxycholesterol to bile acid in human subjects: Is there an alternate pathway favoring cholic acid synthesis?

Despite the fact that most human subjects synthesize about twice as much cholic acid as chenodeoxycholic acid, available evidence suggests that 7α-hydroxycholesterol, the first intermediate in the major pathway for bile acid synthesis, is converted about equally to these two bile acids. Synthesis through the main alternate pathway can not explain this discrepancy because 27-hydroxycholesterol, the first intermediate in that pathway, is converted preferentially to chenodeoxycholic acid. To examine the validity of these contradictory observations, we administered (24-14C)-cholic acid and (24-14C)-chenodeoxycholic acid together with (7β-3H)-7α-hydroxycholesterol on one occasion and (22,23-3H)-27-hydroxycholesterol on a separate occasion to eight normal human subjects. Synthesis of the two primary bile acids was determined by means of standard isotope dilution kinetics of the carbon 14-specific activities of biliary bile acids. Conversion of (7β-3H)-7α-hydroxycholesterol and (22,23-3H)-27-hydroxycholesterol to bile acid was calculated from the tritium/carbon 14 ratio in cholic and chenodeoxycholic acid. For synthesis, the mean ± SEM cholic/chenodeoxycholic ratio was 1.82 ± 0.26. For apparent conversion of (7β-3H)-7α-hydroxycholesterol to bile acid, the mean ± SEM cholic/ chenodeoxycholic ratio was 1.02 ± 0.09, whereas for (22,233H)-27-hydroxycholesterol, the mean ± SEM cholic/chenodeoxycholic ratio was 0.38 ± 0.03. These data imply that, on average, more than 40% of cholic acid in these subjects was synthesized through a pathway that bypassed initial 7α-hydroxylation. However, consideration of all potential candidates for such a pathway raises doubts that any of them contributes substantially to bile acid synthesis. (J Lab Clin Med 2002;139:109-15)

Effects of acipimox on the lipolysis rate in subcutaneous adipose tissue of obese subjects.

Acipimox is a hypolipidaemic agent reducing serum concentrations of triglycerides and non-esterified fatty acids. Acipimox may reduce triglyceride synthesis by decreasing non-esterified fatty acid availability from adipocytes, but this effect has yet to be demonstrated in vivo. Lipolysis after acipimox treatment was examined in subcutaneous adipose tissue of severely obese subjects with associated metabolic disorders. The microdialysis technique was performed in abdominal subcutaneous adipose tissue of eight hyperinsulinaemic subjects. After oral treatment with acipimox, glycerol concentration was determined as an index of lipolysis rate. Blood flow was assessed by the ethanol escape technique. The rates of release of glycerol from human adipose tissue maximally stimulated by norepinephrine were also investigated in the presence of acipimox. Eight weight- and age-matched subjects served as a control group. Under acipimox treatment, basal glycerol release decreased in subcutaneous adipose tissue, whereas no effect was observed on blood flow. In stimulated adipose tissue acipimox showed no effect. In the present study basal glycerol outflow from adipose tissue was inhibited by acipimox. The anti-lipolytic action of the agent may diminish elevated plasma concentrations of free fatty acids in subjects with severe obesity.

The effect of ammonia on omeprazole-induced reduction of gastric acidity in subjects with Helicobacter pylori infection

OBJECTIVE: Omeprazole produces a higher intragastric pH during Helicobacter pylori ( H. pylori) infection than after cure. We tested the hypothesis that this difference is due to the production of ammonia by H. pylori. METHODS: Gastric acidity and acid output (AO) were measured overnight in 12 subjects, with and without omeprazole, before and 1 and 6 months after cure of H. pylori infection. Gastric ammonia ([NH 3]), total bile acid ([TBA]) and protein concentrations and plasma omeprazole levels were measured. RESULTS: During omeprazole, median AO were 0.0 mmol/h before, 0.86 mmol/h ( p = 0.003 vs before cure) at 1 month, and 0.34 mmol/h ( p = 0.02) at 6 months after cure; median NH 3 output was 0.17 mmol/h before, 0.03 mmol/h ( p = 0.002) at 1 month, and 0.02 mmol/h ( p = 0.005) at 6 months after cure. AO and NH 3 output were similar 1 and 6 months after cure. When corrected for [NH 3], AO and gastric pH curves were similar before and after cure. Omeprazole plasma levels increased after cure and gastric [TBA] were unchanged. CONCLUSIONS: The higher pH observed before cure of H. pylori during omeprazole administration is attributable, in large part, to ammonia production. Other acid-neutralizing substances and changes in acid secretion may also be important, but duodenogastric reflux and omeprazole pharmacokinetics are not involved.

The effect of ammonia on omeprazole-induced reduction of gastric acidity in subjects with Helicobacter pylori infection.

Omeprazole produces a higher intragastric pH during Helicobacter pylori (H. pylori) infection than after cure. We tested the hypothesis that this difference is due to the production of ammonia by H. pylori. Gastric acidity and acid output (AO) were measured overnight in 12 subjects, with and without omeprazole, before and 1 and 6 months after cure of H. pylori infection. Gastric ammonia ([NH3]), total bile acid ([TBA]) and protein concentrations and plasma omeprazole levels were measured. During omeprazole, median AO were 0.0 mmol/h before, 0.86 mmol/h (p = 0.003 vs before cure) at 1 month, and 0.34 mmol/h (p = 0.02) at 6 months after cure; median NH3 output was 0.17 mmol/h before, 0.03 mmol/h (p = 0.002) at 1 month, and 0.02 mmol/h (p = 0.005) at 6 months after cure. AO and NH3 output were similar 1 and 6 months after cure. When corrected for [NH3], AO and gastric pH curves were similar before and after cure. Omeprazole plasma levels increased after cure and gastric [TBA] were unchanged. The higher pH observed before cure of H. pylori during omeprazole administration is attributable, in large part, to ammonia production. Other acid-neutralizing substances and changes in acid secretion may also be important, but duodenogastric reflux and omeprazole pharmacokinetics are not involved.

Free and esterified fatty acid and cholesterol synthesis in adult males and its effect on the doubly-labelled water method.

The purpose of the present study was to estimate whole-body fatty acid and cholesterol synthesis in weight-stable adults and to determine the likely effect on the doubly-labelled water (DLW) method for measuring energy expenditure. Synthesis was measured by 2H incorporation over 14 d in six adult males in approximate energy balance following noradrenaline infusion to maximize mobilization of free fatty acid from adipose tissue. The inter-individual variation in synthesis rates was large and in one subject the proportion of free fatty acid synthesized was ten times that of the mean of the rest of the group; the fasting concentration of esterified fatty acid in this subject was five times that of the rest of the group indicating likely violation of the assumptions underlying the calculation of whole-body synthesis. After 14 d of labelling in the other five subjects, 0.9 (SEM 0.3)% of the circulating free fatty acid, 9.3 (SEM 3.0)% of the esterified fatty acid, 14.6 (SEM 2.4)% of the free cholesterol and 28.3 (SEM 3.7)% of esterified cholesterol had been synthesized de novo. A high rate of synthesis correlated with a low pre-dose 2H abundance both within and between lipid classes suggesting that natural 2H abundance variations in some lipid classes may be used to determine their metabolic origin. Whole-body synthetic rates were 8 g/d for fatty acid and 0.3-0.5 g/d for cholesterol. These values correspond to very small errors on DLW-derived estimates of CO2 production; -2.5 litres/d for fatty acid and -0.1 to -0.2 litres/d for cholesterol. These results, obtained in subjects typically consuming a diet with a lower fat and cholesterol content that the typical Western diet, suggest that the DLW method is unlikely to be affected by fatty acid and cholesterol synthesis in subjects in energy balance consuming a typical Western diet.

Effect of supplementation with different doses of DHA on the levels of circulating DHA as non-esterified fatty acid in subjects of Asian Indian background

There is evidence to indicate that the high rates of coronary heart disease and myocardial infarction amongst Indians of Asian descent may be partly related to circulating non-esterified fatty acids (NEFA). As docosahexaenoic acid (DHA,22:6n–3) in NEFA form has been found to exhibit anti-platelet aggregatory and anti-arrythmic potential in vitro, the effect of supplementary DHA was examined in healthy subjects of Asian Indian background. Furthermore, time- and dose-dependent changes in absolute levels of DHA as NEFA or phospholipid (PL) were compared. The subjects consumed 8 capsules daily of placebo (DHA-free) or low DHA (0.75 g/day) or high DHA (1.50 g/day) over 6 wks. Fasting blood samples were drawn at days 0, 21, and 42 for analysis of serum lipid/lipoprotein composition. No significant effect of DHA supplementation on the levels of serum lipid/lipoproteins (including Lp[a]) or blood pressure was found. However, the DHA level in serum phospholipid rose by 167% overall with low-dose supplementation (from 2.4–6.4 mol%) but only by an additional 23% upon doubling the dose from 0.75 g to 1.50 g/day. Furthermore, after 6 weeks of supplementation with 0.75 g or 1.5 g DHA/day, absolute concentrations of DHA as PL were not significantly different from the corresponding 3-week values. Interestingly, the absolute concentrations of serum DHA as NEFA showed a marked rise with low-dose supplementation (by 212% overall, from 2.4 to 7.5 μm) and a further 70% rise (to 12.7 μm) upon doubling the supplementation from 0.75 to 1.50 g/day. As well, the 6-week concentrations (DHA-NEFA) were significantly different than the corresponding 3-week values at both dose levels. Elevation of circulating DHA-NEFA levels via DHA supplementation, as shown herein, to concentrations that exhibit anti-thrombotic and anti-arrhythmic potential in vitro needs to be extended to trials where clinical end-points are determined.—Conquer, J. A., and B. J. Holub. Effects of supplementation with different doses of DHA on the levels of circulating DHA as non-esterified fatty acid in subjects of Asian Indian background.

Analytical method for the determination of urinary 3-phenoxybenzoic acid in subjects occupationally exposed to pyrethroid insecticides

The determination of urinary 3-phenoxybenzoic acid enables exposure to pyrethroid insecticides to be evaluated. A method for the quantitative determination of this metabolite in urine is described. The compound and the internal standard (2-phenoxybenzoic acid) are derivatized with pentafluorobenzylbromide and transformed into pentafluorobenzyl esters, which are determined by gas chromatography with an intermediate polarity capillary column and an electron-capture detector. Before GC analysis, the urinary extracts are purified on LC-Si SPE columns. The proposed method has a detection limit of 0.5 μg/l and a mean recovery of 91.3%. The coefficient of variation of the analytical procedure, evaluated at a concentration of 24.96 μg/l, was 9.58%. Storage of the urine samples for 3 months at −18°C did not lead to significant changes in the concentration of analyte. The method was tested analysing the urine of a farm worker with symptoms of pyrethroid poisoning, occupationally exposed to esfenvalerate.

Abnormal myocardial kinetics of 123I-heptadecanoic acid in subjects with impaired glucose tolerance.

Increased triglyceride accumulation has been observed in the diabetic heart, but it is not known whether the abnormalities in myocardial fatty acid metabolism differ between insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetic patients or whether they are present even prior to overt diabetes. Therefore, we studied myocardial fatty acid kinetics with single-photon emission tomography using 123I-heptadecanoic acid (HDA) in four groups of men: impaired glucose tolerance (IGT) (n = 13, age 53 +/- 2 years, mean +/- SEM), IDDM (n = 8, age 43 +/- 3 years), NIDDM (n = 10, age 51 +/- 2 years) and control subjects (n = 8, age 45 +/- 4 years). Echocardiography and myocardial perfusion scintigraphy (IGT and NIDDM groups) were performed to study cardiac function and flow. In the IGT subjects, myocardial HDA beta-oxidation index was reduced by 53% (4.6 +/- 0.4 vs 9.7 +/- 1.0 mumol .min-1.100 g-1, p < 0.01) and HDA uptake by 34% (3.7 +/- 0.2 vs 5.6 +/- 0.3% of injected dose 100g, p < 0.01) compared with the control subjects. The fractional HDA amount used for beta-oxidation was lower in the IGT compared with the control subjects (43 +/- 4 vs 61 +/- 4%, p < 0.05). NIDDM patients also tended to have a lowered HDA beta-oxidation index, whereas IDDM patients had similar myocardial HDA kinetics compared to the control subjects. Myocardial perfusion imaging during the dipyridamole-handgrip stress was normal both in the IGT and NIDDM groups, indicating that abnormal myocardial perfusion could not explain abnormal fatty acid kinetics. In conclusion, even before clinical diabetes, IGT subjects show abnormalities in myocardial fatty acid uptake and kinetics. These abnormalities may be related to disturbed plasma and cellular lipid metabolism.

A dose‐ranging study of ranitidine and its effect on intragastric and intra‐oesophageal acidity in subjects with gastro‐oesophageal reflux disease

This randomized, double-blind, single-centre, crossover study was designed to assess the effects of three regimens of ranitidine (150 mg b.d., 300 mg b.d. and 300 mg q.d.s.) and placebo on intra-oesophageal and intragastric pH in subjects with gastro-oesophageal reflux disease (GERD). Twenty-six subjects were screened, and 9 were evaluable by the admission criteria. These 9 subjects received each of the regimens for 72 h, and a wash-out period of at least 48 h followed each dosing period. Standard meals and beverages were provided. With increasing doses of ranitidine, 24-h intragastric mean H+ and integrated H+ fell, and the percentage of the time the pH was equal to or greater than 4 (% time pH > or = 4) rose: the minimum effective dose for these effects was ranitidine 300 mg daily. With increasing doses of ranitidine there was also a progressive decline in mean 24-h intra-oesophageal H+ and integrated H+, and increasing % time pH > or = 4. The minimal effective dose was 300 mg daily for intra-oesophageal mean H+ and integrated H+, and 600 mg for % time pH > or = 4. The minimal effective dose to decrease the number of reflex episodes was 1200 mg ranitidine. For the daytime upright position, a dose effect of increasing ranitidine was also seen, with minimal effective ranitidine doses of 300 mg for a decrease in mean H+, and 1200 mg for % time pH > or = 4. If these higher doses of ranitidine are confirmed to be more effective than the standard 150 mg b.d. regimen for the treatment of patients with gastro-oesophageal reflux disease, then the mechanism of this action probably relates to the lower exposure of the oesophageal mucosa to acid.

Toxicological and immune findings in workers exposed to pentachlorophenol (PCP).

Pentachlorophenol (PCP) is a pesticide used worldwide in industrial and domestic applications. Data available on the effects of technical-grade PCP on the immune system are insufficient and equivocal; some data indicate inhibitory effects, whereas others suggest stimulating effects. This study was performed to evaluate toxicological and immune findings in 32 subjects who had prolonged exposure to PCP in a wood factory and in 37 controls. PCP concentrations were determined in plasma and urine of all subjects. Lymphocyte subsets of CD3-, CD4-, and CD8-positive cells were evaluated, and the proliferative response of peripheral blood mononuclear cells (PBM) to mitogens was assessed. The results suggested the absence of major laboratory and clinical signs of PCP-dependent immune deficiency. A weak effect of long-term exposure to PCP on the functional immune response could not be ruled out because of the finding of a decreased response to 5% PHA in the high-exposure group. A weak effect against hepatocyte membrane was evidenced by the finding of raised serum concentration of glycocholic, taurodeoxycholic, and glycochenodeoxycholic acids in subjects directly exposed to PCP for more than 10 y.

Postprandial lipoprotein (a) response to a single meal containing either saturated or ω-3 polyunsaturated fatty acids in subjects with hypoalphalipoproteinemia

We have recently reported that the apolipoprotein (apo) B-100-apo(a) complex, the protein moiety of lipoprotein(a) [Lp(a)], has a high affinity for triglyceride (TG)-rich particles (TRP) and that this complex can affiliate with endogenous TG-rich lipoproteins. To shed more light on the apo B-100-apo(a) complex associated with plasma TRP during postprandial lipidemia, we fed five male subjects presenting with primary hypoalphalipoproteinemia (HP) and four male controls a single fat meal (60 g/m 2) containing saturated fatty acids (SFA) and, 6 weeks later, an isocaloric meal containing ω-3 polyunsaturated fatty acids. The subjects were phenotyped for plasma Lp(a) and apo C-III levels, apo(a) and apo E isoforms, and lipoprotein lipase and hepatic lipase activities. Vitamin A was included in the meal as a marker of intestinally derived TRP. Following the SFA meal, three of the HP subjects showed a decrease in plasma levels of Lp(a) that lasted 10 to 12 hours in the presence of an increased hypertriglyceridemic response. Two HP subjects who had low preprandial lipoprotein lipase activity and elevated plasma apo C-III levels showed an increase in plasma Lp(a) levels along with the hypertriglyceridemic excursion. However, in all cases, inclusive of the controls, there was an elevation in plasma levels of TRP of S f greater than 1,000 that contained apo B-100-apo(a) 6 to 8 hours after the meal. This TRP excursion appeared not to be related to the basal levels of plasma Lp(a), high-density lipoprotein (HDL) cholesterol, TGs, or apo(a) and apo E isoforms, and it did not coincide with the retinyl ester peak. These TRP species were purified through an anti-apo(a) Sepharose column and were found to contain apo(a) linked to apo B-100, but not free apo B-100 or apo B-48. The changes in postprandial Lp(a) levels in the subjects fed ω-3 fatty acids were comparatively more modest than those seen after the SFA meal. Taken together, the results indicate that the postprandial response of plasma Lp(a) to a fat meal is variable, but it is consistently attended by an accumulation of TRP containing apo B-100-apo(a) that is probably of hepatic origin and independent of either preprandial or postprandial total plasma triglyceride levels or preprandial Lp(a) levels. Thus, several factors appear to contribute to the plasma Lp(a) response to a fat meal; type of fat, lipoprotein lipase, and apo C-III may be among these factors.

Differential effects of nicotinic acid in subjects with different LDL subclass patterns

Twenty-six subjects (20 male, 6 female) at high risk for CAD events were treated with moderate doses of nicotinic acid to investigate whether there was a differential lipoprotein response in patients with different LDL subclass patterns. Subjects were selected to have either pattern A (predominance of large LDL, peak particle diameter > 262 Å, n = 9) or pattern B (predominance of small LDL, peak particle diameter < 255 Å, n = 17) as assessed by 2–16% gradient gel electrophoresis of plasma. Nicotinic acid dose was similar in pattern A (2111 ± 651 mg/day) and pattern B subjects (1875 ± 698 mg/day). Total cholesterol and LDL cholesterol decreased by similar amounts in pattern A (-41 ± 26 mg/dl and −37 ± 18 mg/dl) and pattern B (−51 ± 44 mg/dl and −44 ± 45 mg/dl) subjects. Triglycerides tended to be reduced more in pattern B subjects (−100 ± 175 mg/dl) compared to pattern A subjects (−23 ± 34 mg/dl) although this difference was not statistically significant ( P = 0.08 for triglycerides log transformed). HDL cholesterol increased significantly more in the pattern B group (11.9 ± 14.2 mg/dl) compared to pattern A subjects (0.7 ± 8.5 mg/dl), ( P < 0.04). Similarly, LDL particle diameter increased significantly more in the pattern B subjects (9.8 ± 6.9 Å) compared to the pattern A subjects (3.6 ± 3.0 Å), ( P < 0.02). All pattern B subjects who achieved a plasma triglyceride < 140 mg/dl converted to pattern A. The differential effect of nicotinic acid in individuals with differing LDL subclass profiles may contribute to intraindividual variation in response to this drug and its effect on coronary atherosclerosis.

Serum Sialic Acid in Subjects with Hyperlipidaemia

Serum Sialic Acid in Subjects with Hyperlipidaemia

Ursodeoxycholic acid therapy in chronic active hepatitis

A 41 year old woman developed chronic active hepatitis with prominent cholestasis. She was treated with prednisolone over 3 years with symptomatic benefit and improvement in serum biochemistry. However, various steroid-related side effects were encountered and steatorrhoea eventually occurred with very troublesome nocturnal diarrhoea. Therapy with ursodeoxycholic acid 750 mg daily was started. Serum alanine aminotransferase and gamma-glutamyl transferase normalized for the first time since her illness began. Steatorrhoea was abolished. There was good control of symptoms as prednisolone therapy was gradually reduced. However, when prednisolone was completely withdrawn there was a prompt biochemical deterioration. Addition of low-dose azathioprine has maintained normal blood tests over 24 months without return of the original symptoms. There are no side effects of ursodeoxycholic acid in subjects without gallstones and this agent may be effective treatment for cholestatic liver disease.

Concentrations of cholestenoic acids in plasma from patients with reduced intestinal reabsorption of bile acids.

The concentrations of 3 beta-hydroxy-5-cholestenoic acid, 3 beta,7 alpha-dihydroxy-5-cholestenoic acid, and 7 alpha-hydroxy-3-oxo-4-cholestenoic acid were determined in plasma from patients treated with cholestyramine or subjected to resection of the ileum or colon. The values were compared with those for conjugated and unconjugated C24 bile acids. Patients with an intact ileum but without colon had normal levels of cholestenoic acids. Patients treated with cholestyramine or with ileal resection had elevated levels of 7 alpha-hydroxy-3-oxo-4-cholestenoic acid (median values 189 and 233 ng/ml, respectively, compared to 85 ng/ml in controls). The levels of the other two C27 acids were normal in cholestyramine-treated and low in ileoresected patients and were positively correlated to each other but not to the 3-oxo-delta 4 acid. There were no consistent correlations between the levels of C27 acids and those of conjugated or unconjugated C24 bile acids. The results indicate an increased formation of 7 alpha-hydroxy-3-oxo-4-cholestenoic acid in subjects having a stimulated activity of cholesterol 7 alpha-hydroxylase.

Increased serum IgG antibodies reactive with lipoteichoic acids in subjects with gingivitis.

The aim of the present study was to assess serum antibodies reactive with lipoteichoic acids (LTAs) in test panels with and without gingivitis. LTA‐rich preparations were obtained from Streptococcus mutans and from Staphylococcus aureus cells. Serum IgG antibodies to those LTAs, and to commercially available lipopolysaccharide (LPS) from Escherichia coli strain 055:B5 were measured in enzyme‐linked immunosorbent assays (ELISA). The LPS was included as a negative control. Serum antibodies reactive with LTAs showed a significant (p&lt;0.05) age‐dependent rise in young people (aged 4 to 24 years), and then leveled out. Ten days experimental gingivitis was induced by means of frequent sucrose rinses in 10 volunteers (all 19‐yr‐old). The mean serum antibody levels to the LTA‐rich extracts increased 3‐ to 4‐fold during the test period, whereas the mean antibody level to LPS remained unchanged. Ten periodontally healthy adult persons were matched for age (3‐yr intervals) and teeth present (± 3 teeth) with 10 adult subjects with chronic ginvititis, but no alveolar bone loss. The mean age was about 50 yr. The chronic gingivitis group showed statistically significant, i.e. 4‐ to 5‐fold higher antibody levels reactive with the LTAs. The corresponding difference in anti‐LPS levels was insignificant. Dental plaque thus triggers significant systemic antibody responses to LTAs.

Effects of intravenous infusion of urographic contrast agents on glomerular filtration rate, serum concentration and urinary excretion of uric acid in subjects with normal renal function.

The utilization of modern triiodinated radiocontrast agents for intravenous urography (IVU) is widely considered as a very safe procedure in patients free of currently well defined risk factors, amongst which the prominent ones are preexisting renal disease and diabetes mellitus complicated by deteriorated renal function (1,2,3). Whereas the incidence of nephrotoxicity accidents is extremely low in patients with no preexisting renal insufficiency, the risk of an acute, and sometimes definitive, deterioration of renal function following administration of radiocontrast agents has been evaluated as high as 90 % in insulin dependent diabetic patients with severe preexisting renal impairment (1).

Use of two different deoxyribonucleic acid probes to detect Y chromosome deoxyribonucleic acid in subjects with normal and altered Y chromosomes

Four experiments evaluated the sensitivity and specificity of molecular techniques to detect human Y chromosome deoxyribonucleic acid. In experiment I, electrophoretic separation of normal male deoxyribonucleic acid fragments after digestion with endonuclease Hae III revealed two male-specific bands of 3.4 and 2.1 kilobase (kb). These bands were not visible if the fraction of male deoxyribonucleic acid in mixed samples was less than 0.3. In experiment II, by means of a repetitive copy Y deoxyribonucleic acid probe (pS4) mapped to Yq12, a male-specific 2.3 kb band was detectable in mixtures of 2.5 ng of male deoxyribonucleic acid and 997.5 ng of 45,X female deoxyribonucleic acid. In experiment III, hybridization with the pS4 probe was performed on the deoxyribonucleic acid of 20 subjects with a normal or a variant Y chromosome. In experiment IV, deoxyribonucleic acid from the same subjects was hybridized to a single copy probe (4B-2) mapped to the Yq11 region. Deoxyribonucleic acid from category A subjects (n = 8) with cytologically normal Y chromosomes hybridized to both deoxyribonucleic acid probes. Deoxyribonucleic acid from category B subjects (n = 2), including a variant Y chromosome that was negative for Q-banding but positive for C-bands, hybridized with the distal pS4 and proximal 4B-2 probes. Deoxyribonucleic acid from category C subjects (n = 10) with variant Y chromosomes uniformly negative for Q- and C-bands, did not hybridize with the pS4 probe. Deoxyribonucleic acid from three of the 10 category C subjects did hybridize to the more proximal sequence-detecting 4B-2 probe. Deoxyribonucleic acid from the remaining seven subjects in category C did not hybridize with either of the deoxyribonucleic acid probes.

Carbohydrate metabolism in pregnancy: XVII. Diurnal profiles of plasma glucose, insulin, free fatty acids, triglycerides, cholesterol, and individual amino acids in late normal pregnancy

Diurnal profiles have been constructed for glucose, free fatty acids (FFA), triglycerides, cholesterol, and ten neutral amino acids in subjects with normal carbohydrate metabolism during late pregnancy and in age- and weight-matched nongravid women. Samples of blood were secured during a 24 hour period while the subjects were receiving a liquid formula diet (containing 2,110 kcal with 275 gm carbohydrate and 75 gm protein) in three equal feedings at 0800, 1300, and 1800 hours. Postprandial excursions for most nutrients, as well as plasma concentrations after overnight fast and before each meal, were significantly different in the pregnant subjects. The studies indicate that criteria of normalcy based on observations in nongravid women cannot be invoked to assess fuel homeostasis in late pregnancy, and that separate criteria are necessary to evaluate nutrient regulation at this time.