Experimental model of pyridoxine (B6) deficiency-induced neuropathy.

A pyridoxine (B6) dietary deficiency was studied in female adult Sprague-Dawley rats by hind-limb walking-track analysis. Serum levels of pyridoxine and three metabolites were quantified by high-pressure liquid chromatography with fluorescence measurement. Morphometric analysis of the sciatic and posterior tibial nerves (from within the tarsal tunnel) was performed after 1 year on a diet deficient in vitamin B6. The B6-deficient rats developed abnormal walking-track patterns by 8 months, and these track parameters were different from age- and sex-matched normal diet control rats at the p < 0.05 level. Adding B6 at 10 parts per million to the diet then partially corrected these parameters, whereas the addition of 30 parts per million B6 corrected the abnormal pattern completely. Serum pyridoxal concentration correlated with the functional parameters, dropping from a mean of 115 mg per liter to 39.5 mg per liter (p < 0.05), and correcting with the B6 additive. Morphometric analysis demonstrated that the B6-deficient nerve from the tarsal tunnel had a decreased nerve fiber density (p < 0.001), with a normal total myelinated nerve fiber number, and an increased axon-to-myelin ratio (p < 0.003). It is concluded that a diet totally deficient in vitamin B6 results in a peripheral neuropathy.

Serum vitamin A concentration is elevated in idiopathic intracranial hypertension.

OBJECTIVE: The primary purpose was to investigate whether serum vitamin A concentration is associated with idiopathic intracranial hypertension (IIH). The secondary aim was to obtain pilot data regarding the amount of vitamin A ingested by patients and controls. BACKGROUND: Vitamin A is an attractive candidate mediator of IIH as many of the symptoms and signs of hypervitaminosis A mimic those of IIH. METHODS: We prospectively determined serum retinol and retinyl ester concentration in 16 women with IIH and 70 healthy young women. Using a survey instrument, we also determined the average daily vitamin A ingestion in a convenience sample of patients and controls. RESULTS: Serum retinol concentration was significantly higher in the patient group (median 752 ug/L) compared with the control group (median 530 ug/L), even after adjusting for age and body mass index (p < 0.001). Retinyl ester concentration, however, was similar in the patient (median 48 ug/L) and control (median 41 ug/L) groups (p = 0.32). There was no significant correlation between serum retinol concentration and body mass index in the patients (r = 0.16) or controls (r = -0.02). Finally, there was no significant difference in the amounts of vitamin A ingested by the patients or controls, although the small number of subjects in both groups reduced the power of this conclusion. CONCLUSIONS: Elevated serum retinol concentration is associated with IIH. Obesity, by itself, does not explain these higher levels. Patients may ingest an abnormally large amount of vitamin A, metabolize it abnormally, or be unusually sensitive to its effects. Alternatively, elevated level of serum retinol may reflect an epiphenomenon of another variable we did not measure or a nonspecific effect of elevated retinol binding capacity.

Predictive value of electrophoretically detected lipoprotein(a) for coronary heart disease and cerebrovascular disease in a community-based cohort of 9936 men and women.

BACKGROUND: Elevated lipoprotein(a) [Lp(a)] levels have been associated with the presence of atherosclerotic disease. However, the results of prospective studies of Lp(a) and cardiovascular disease have been contradictory. METHODS AND RESULTS: From 1968 through 1982, lipoprotein analysis was performed in 11,335 Olmsted County residents. Quantitative cholesterol and triglycerides were obtained along with semiquantitative Lp(a) levels based on electrophoretic pattern. Lp(a) bands were scored from 0 (absent) to 3 (increased). A cohort of 4967 men and 4968 women with no prior history of atherosclerotic disease who had baseline Lp(a) determinations were followed up for 14 years for development of coronary artery disease (CAD) and cerebrovascular disease (CVD). During 131,330 person-years of follow-up, there were 1848 CAD events and 841 CVD events. Age, diabetes, hypertension, cholesterol, and triglycerides were significantly and independently associated with an increased risk of CAD and CVD in men and women. There was a significant increase in the adjusted hazards ratio for CAD with increasing Lp(a) levels for men and women. For Lp(a) level 3, the hazard ratio was 1.9 (range, 1.3 to 2.9) in women and 1.6 (range, 1.0 to 2.5) in men. The adjusted hazard ratio for CVD showed an irregular association with Lp(a) levels in men and no association in women. CONCLUSIONS: In this cohort of 9936 men and women initially free of cardiovascular disease who were followed up for 14 years, Lp(a) was a significant predictor of risk of future CAD. Lp(a) was a weak risk factor for CVD in men and was not a significant predictor of CVD risk in women.

Environmental chemical exposures and disturbances of heme synthesis.

Porphyrias are relatively uncommon inherited or acquired disorders in which clinical manifestations are attributable to a disturbance of heme synthesis (porphyrin metabolism), usually in association with endogenous or exogenous stressors. Porphyrias are characterized by elevations of heme precursors in blood, urine, and/or stool. A number of chemicals, particularly metals and halogenated hydrocarbons, induce disturbances of heme synthesis in experimental animals. Certain chemicals have also been linked to porphyria or porphyrinuria in humans, generally involving chronic industrial exposures or environmental exposures much higher than those usually encountered. A noteworthy example is the Turkish epidemic of porphyria cutanea tarda produced by accidental ingestion of wheat treated with the fungicide hexachlorobenzene. Measurements of excreted heme precursors have the potential to serve as biological markers for harmful but preclinical effects of certain chemical exposures; this potential warrants further research and applied field studies. It has been hypothesized that several otherwise unexplained chemical-associated illnesses, such as multiple chemical sensitivity syndrome, may represent mild chronic cases of porphyria or other acquired abnormalities in heme synthesis. This review concludes that, although it is reasonable to consider such hypotheses, there is currently no convincing evidence that these illnesses are mediated by a disturbance of heme synthesis; it is premature or unfounded to base clinical management on such explanations unless laboratory data are diagnostic for porphyria. This review discusses the limitations of laboratory measures of heme synthesis, and diagnostic guidelines are provided to assist in evaluating the symptomatic individual suspected of having a porphyria.

Fecal marker variability in colorectal cancer: calprotectin versus hemoglobin.

BACKGROUND: Blood products like hemoglobin are problematic as markers for colorectal neoplasia because bleeding is intermittent. Levels of calprotectin, a leukocyte-derived protein, are increased in stools from colorectal cancer patients. However, this blood constituent may gain luminal access via interstitial leukocyte migration, which could be a less variable mechanism of entry than bleeding. METHODS: To correlate the levels of and to compare the variability of fecal calprotectin and hemoglobin, quantitative assays were performed independently on multiple serially collected stools from 14 patients with colorectal cancer. Marker level association was estimated with Pearson's correlation coefficient, and variation estimated with an analysis of variance model. RESULTS: Fecal calprotectin and hemoglobin levels were discordant in 55 (50%) of 110 matched aliquots, and marker levels failed to correlate. The estimated between-subject correlation was -0.10 (95% CI, -0.60 to 0.46), and mean within-subject correlation -0.27 (95% CI, -0.73 to 0.34). The between-stool coefficient of variation was less for calprotectin (22%) than for hemoglobin (80%). CONCLUSIONS: In patients with colorectal cancer, the mechanism of luminal calprotectin entry appears to be both different from and less erratic than bleeding.

The porphyrias [corrected]: characteristics and laboratory tests.

The term porphyria represents seven neuropathic and/or dermopathic diseases caused by disturbances of the heme-forming system. Accumulation of the heme precursor, delta-aminolevulinic acid (delta ALA), is associated with the neurologic manifestations, and accumulation of photoreactive by-products, the porphyrins, causes cutaneous photosensitivity and dermopathic manifestations. The degrees of expression range from mild to severe, and acute episodes of neuropathic porphyrias can progress to paralysis and life-threatening respiratory failure. Diagnostic laboratory tests include quantitation of delta ALA, porphobilinogen, and porphyrins in blood, urine, and feces and analysis of activities of enzymes of the heme-forming system. Both inheritable and noninheritable forms of porphyria can be induced by toxic chemicals, and, therefore, tests for porphyria are becoming included increasingly in examinations of persons who have experienced problematic chemical exposures.

Accuracy of fecal occult blood screening for colorectal neoplasia. A prospective study using Hemoccult and HemoQuant tests.

OBJECTIVES: To define the validity of fecal blood as a marker for colorectal neoplasia in the screening setting and to compare yields by Hemoccult and HemoQuant fecal occult blood screening tests. DESIGN: A multicenter masked comparison of fecal blood test results against structural colorectal evaluations and longitudinal follow-up, serving as criterion standards, in nonreferred subjects at risk for colorectal neoplasia. SETTING: Communities, primary care centers, referral centers. PARTICIPANTS: Two groups: (1) 1217 patients aged at least 18 years undergoing routine structural surveillance evaluations following curative resection of a colorectal tumor and (2) 12312 relatives of colorectal cancer patients aged at least 50 years. INTERVENTIONS: Blinded Hemoccult II and HemoQuant testing on three mailed-in stool samples per subject. MAIN OUTCOME MEASURE: Sensitivity of fecal blood tests for colorectal neoplasia. RESULTS: In the postresection group, surveillance evaluations revealed 46 malignant colorectal neoplasms and 402 polyps. At matched specificity, sensitivity of either test for cancer was 26% (95% confidence interval, 13% to 39%). Hemoccult was positive in 21% of intraluminal recurrences, 33% of all new primary tumors, and 29% of Dukes A or B cancers; HemoQuant was elevated in 24%, 28%, and 29%, respectively. Sensitivity for polyps 1.0 cm or larger was 13% by Hemoccult and 11% by HemoQuant. In the group of relatives, estimated sensitivity for cancer at 1 to 3 years of follow-up was 25% to 33% by Hemoccult, not significantly different from the 29% to 43% by HemoQuant. CONCLUSIONS: Based on our observations in the screening setting, fecal blood appears to be a poor marker for colorectal neoplasia. Most cancers and the vast majority of polyps will be missed. Hemoccult and HemoQuant are similarly insensitive.

Cod liver oil alters platelet-arterial wall response to injury in pigs.

In 36 normolipemic pigs randomized to a 4-week feeding with regular pig chow (n = 18, control group) or chow supplemented with cod liver oil (1 ml/kg per day) (n = 18, treated group), treatment with cod liver oil produced a significant decrease in serum cholesterol, low density lipoprotein cholesterol, and triglycerides. Deep carotid arterial wall injury (media exposed) by balloon angioplasty was associated with less 111In-labeled platelet deposition (24.6 +/- 4.8 x 10(6)/cm2 versus 62.5 +/- 17.0 x 10(6)/cm2, p less than 0.05; difference, -33.8 x 10(6)/cm2; 95% confidence interval [CI], -1.9 x 10(6)/cm2 to -73.9 x 10(6)/cm2) and injury-related vasoconstriction (21.3 +/- 2.2% versus 30.9 +/- 2.9%, p less than 0.05; difference, -9.6%; 95% CI, -2.2% to -17.0%) in the cod liver oil-treated group than in the control group; with mild injury (media not exposed), platelet deposition was low and unchanged (6.2 +/- 0.5 x 10(6)/cm2 versus 7.8 +/- 0.7 x 10(6)/cm2; difference, -1.6 x 10(6)/cm2; 95% CI, -1.1 x 10(6)/cm2 to +4.3 x 10(6)/cm2), but associated vasoconstriction was reduced respectively (16.3 +/- 2.0% versus 23.0 +/- 2.2%, p less than 0.05; difference, -6.7%; 95% CI, -0.6% to -12.8%). When arterial blood from cod liver oil-treated pigs superfused normal aortic media ex vivo, platelet deposition onto the normal aortic media was lower than when arterial blood from control pigs superfused the normal aortic media (43.7 +/- 8.8 x 10(6)/cm2 versus 66.8 +/- 13.0 x 10(6)/cm2, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Lovastatin therapy for cholesterol ester storage disease in two sisters.

We administered lovastatin to two sisters, aged 4 and 17 years, who had cholesterol ester storage disease, an autosomal recessive disorder manifested by hypercholesterolemia and hypertriglyceridemia. The drug, a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, was taken orally for 6 months. Serum lipid concentrations were determined monthly. Computed tomography of the liver was performed before and during therapy to evaluate liver fat content. The younger sister had liver biopsies before and after 6 months of lovastatin therapy to assess hepatic cholesterol stores. Both patients had marked decreases in serum levels of cholesterol, triglycerides, and low-density lipoprotein-cholesterol; high-density lipoprotein-cholesterol levels increased. Computed tomography during treatment demonstrated a significant increase in linear attenuation, suggesting a decreased liver fat content. Liver tissue obtained 6 months after lovastatin therapy was initiated had 13% less esterified cholesterol than the liver sample obtained before treatment. We conclude that lovastatin may be effective in treating children with cholesterol ester storage disease.

Is the high concentration of ascorbic acid in the eye an adaptation to intense solar irradiation?

Ascorbic acid is known to exist in high concentration in the aqueous humor of the eye in many species. It has been observed that diurnal mammals have a very high concentration in aqueous humor whereas nocturnal mammals do not. It has been hypothesized that ascorbic acid protects the eye from the harmful effects of sunlight. We have discovered that of two closely related species of spiny mice, the diurnal species (Acomys russatus) has a concentration in aqueous humor that is 35 times higher than that of the nocturnal species (Acomys cahirinus). Studies of these two species may be fruitful to extend what is known about adaptation of the eye to protect itself from intense solar radiation.

Heterogeneity of lipoprotein Lp(a) and apolipoprotein(a).

We have purified Lp(a) lipoproteins from sera of four subjects by ultracentrifugation, selective precipitation, and chromatofocusing. Each subject had two forms of serum Lp(a) that were separable by chromatofocusing. We purified apolipoprotein (a) [apo(a)] from the eight isolated Lp(a)s and obtained only one form of apo(a) from each subject. The four apo(a)s seen on sodium dodecyl sulfate-polyacrylamide gel electrophoresis had different apparent molecular masses, ranging from 275 to 440 kDa. Chemical deglycosylation of the smallest apo(a) yielded a 235 kDa protein, which may be a core protein structure common to all apo(a)s. We conclude that there are many forms of serum Lp(a) and apo(a). The heterogeneity of serum Lp(a) particles can be ascribed in part to differences in size of apo(a), but other factors must account for the existence within a single patient of different Lp(a)s that contain apparently identical apo(a). One must consider the heterogeneity of Lp(a) when designing assays for this lipoprotein.

Measurement of degraded fecal hemoglobin-heme to estimate gastrointestinal site of occult bleeding. Appraisal of its clinical utility.

Hemoglobin-heme is variably converted to porphyrin during enterocolic transit. This intestinal converted fraction, as measured by HemoQuant, was elevated as a predictor of the occult bleeding site in 152 patients with discrete lesions. The intestinal converted fraction, expressed as the percentage of total fecal hemoglobin, was similar with upper gastrointestinal and proximal colon lesions. Within the colon, values trended downward with more distal location: means +/- standard deviations were 18 +/- 14 proximal colon, 16 +/- 15 sigmoid, and 10 +/- 10 rectum. The amount of fecal blood also affected the intestinal converted fraction; correcting for hemoglobin concentration improved separation by site. Corrected intestinal converted fraction values were significantly lower with rectal (P less than 0.0005) and sigmoid (P less than 0.02) lesions than with proximal colon lesions. Unfortunately, large within-site variation caused considerable overlap between sites. We conclude that the intestinal converted fraction is influenced by the site and amount of bleeding. However, its clinical utility is compromised by substantial individual differences in luminal hemoglobin metabolism.

Influence of aspirin and ethanol on fecal blood levels as determined by using the HemoQuant assay.

We sought to determine the short-term effects of use of aspirin and ethanol on fecal occult blood levels measured with the HemoQuant assay. A factorial design was used to study 68 healthy volunteers randomized to receive various doses of aspirin, ethanol, or a combination of both for either 1 or 3 days. Fecal hemoglobin concentrations were measured before and after drug ingestions. Moderate quantities of ethanol (300 ml of 5% or 30 ml of 50% three times nightly) did not cause significant fecal blood elevation unless aspirin was administered concomitantly (P = 0.05). High-dose aspirin alone, 975 mg three times daily, induced abnormal blood loss (P less than 0.01). The highest HemoQuant levels were usually noted after concomitant administration of aspirin and ethanol at maximal doses for 3 days (P less than 0.005), some HemoQuant levels approaching 5 times the normal value. We conclude that, in a short-term analysis, social consumption of ethanol is unlikely to interfere with fecal blood testing but therapeutic doses of aspirin will.

The relationship between diuretics and serum cholesterol in Hypertension Detection and Follow-up Program participants.

The effect of diuretics, mainly chlorthalidone, on serum cholesterol was studied in 7,006 of the Hypertension Detection and Follow-up Program (HDFP) hypertensive patients not on antihypertensive medication at baseline. Several investigators have reported that diuretic therapy increases serum cholesterol in treated subjects. However, data from two long-term studies indicated that no increase in cholesterol occurred after two years of diuretic treatment. In the present study, yearly changes in serum cholesterol in hypertensives treated with diuretics were observed. The results were in agreement with those reported from both short-term and long-term studies, in that a significant increase in cholesterol was observed in six months to one year into the study but not from the second to the fifth year of therapy. In fact, the serum cholesterol levels were the same as baseline values after two years of drug treatment and decreased slightly thereafter. In the untreated group, no change or a decrease in serum cholesterol was observed during the course of the study. The possible causes for changes in serum cholesterol concentration such as regression to the mean, change in body weight, baseline cholesterol concentration, and the action mechanism of diuretic drugs are discussed.

Analytical assessment of Broviac catheter occlusion.

Eight of 92 consecutive silastic central venous catheters used for home parenteral nutrition occluded. Six of the eight had patency restored by the instillation of urokinase or streptokinase into the catheter. The thrombus in one of the two catheters that was not reopened with thrombolytic agents was studied in detail by electron microscopy, x-ray dispersive analysis, solubility in isopropyl alcohol-diethyl ether (1:1, v:v), and thin-layer chromatography of extracted lipids. Electron microscopy found the clot to be an amorphous mass without features to suggest crystalline properties. The x-ray dispersive analysis showed that the only elements which were significantly increased were chloride and silicon and the silicon detected was likely from the underlying catheter. Treatment with isopropyl alcohol-diethyl ether left an insoluble, flaky residue that resembled protein from a thrombus. Thin-layer chromatography detected a lipid profile suggestive of circulating endogenous fat instead of the fat that was infused through the catheter.

The relationship of placental grade by ultrasound to markers of fetal lung maturity.

Seventy-two amniocenteses with concurrent placental grading by ultrasound were performed during 66 pregnancies. No relationship was observed between placental grade and the mean ratio of lecithin to sphingomyelin (L/S) or the phosphatidylglycerol concentration. Both placental grade and fetal lung maturity were interrelated by the independent variable of gestational age. The latter may explain the trend observed between a mature L/S ratio and the placental grade. Grade 3 placentas were present in only 20% of patients studied at 37 weeks of gestation or later (12 of 61 patients), and in every instance a Grade 3 placenta was associated with an absence of neonatal respiratory distress.

Total cholesterol and lipoproteins in school children: prediction of coronary heart disease in adult relatives.

The distribution of risk factors and the prevalence of coronary heart disease (CHD) were studied in 850 first- and second-degree relatives of 98 healthy index cases selected from 3666 school children surveyed for lipid levels in Rochester, Minnesota. Three groups of families were based on an index child's total plasma cholesterol level: 18 families with a child in less than the fifth percentile (low-cholesterol group), 47 with a child in the fifth to ninety-fifth percentiles (middle-cholesterol group) and 33 with a child in greater than the ninety-fifth percentile (high-cholesterol group). The children's cholesterol levels clustered with those of their relatives; mortality due to CHD before age 65 was increased by 2.5 times in grandfathers of index cases in the high-cholesterol group compared with those of the middle-cholesterol group (p less than 0.016). The prevalence of CHD in all the grandfathers was associated with an index child's total cholesterol, more strongly associated with an index child's low-density lipoprotein cholesterol level and most strongly associated with an index child's high-density lipoprotein cholesterol level as a fraction of total cholesterol. This study establishes that childhood lipid and lipoprotein levels from a single cross-sectional survey identify families at elevated risk for CHD.