Relative Proportions Of Lipids Research Articles

Tear Analysis and Lens-tear Interactions: Part II. Ocular Lipids—Nature and Fate of Meibomian Gland Phospholipids

Published data indicate that the polar lipid content of human meibomian gland secretions (MGS) could be anything between 0.5% and 13% of the total lipid. The tear film phospholipid composition has not been studied in great detail and it has been understood that the relative proportions of lipids in MGS would be maintained in the tear film. The purpose of this work was to determine the concentration of phospholipids in the human tear film. Liquid chromatography mass spectrometry (LCMS) and thin layer chromatography (TLC) were used to determine the concentration of phospholipid in the tear film. Additionally, an Amplex Red phosphatidylcholine-specific phospholipase C (PLC) assay kit was used for determination of the activity of PLC in the tear film. Phospholipids were not detected in any of the tested human tear samples with the low limit of detection being 1.3 μg/mL for TLC and 4 μg/mL for liquid chromatography mass spectrometry. TLC indicated that diacylglycerol (DAG) may be present in the tear film. PLC was in the tear film with an activity determined at approximately 15 mU/mL, equivalent to the removal of head groups from phosphatidylcholine at a rate of approximately 15 μM/min. This work shows that phospholipid was not detected in any of the tested human tear samples (above the lower limits of detection as described) and suggests the presence of DAG in the tear film. DAG is known to be at low concentrations in MGS. These observations indicate that PLC may play a role in modulating the tear film phospholipid concentration.

Comparative study of crude oils from the Machete area in the Eastern Venezuelan Basin by pyrolysis of asphaltenes

This work is an analysis of crude oil samples from the two most recent producing wells in the Machete area (Orinoco Tar Belt, Venezuela). The aim is to determine the type of environment in which the precursor organic materials were deposited. In spite of the fact that the degree of maturity and the biodegradation of the two crude oils are similar, their characterization leads us to conclude that they have very distinctive and different origins. The comparative study was performed by separating their main fractions, pyrolysis of asphaltenes, and further identification of several indicators (aromatic, polar and sulfur compounds, linear aliphatic hydrocarbons, and cadalene). Moreover, several biomarkers (terpanes, hopanoids and steranes) present in the saturated fractions obtained from the two crude oils were analyzed by using gas chromatography combined with mass spectrometry (GC–MS). The statistical study of geochemical indicator values and relative proportions of lipid and lipid-like biomarkers present in products from asphaltene pyrolysis shows a high probability of there being two distinct crude oil families from the Machete area.

Efficacy of a next-generation, lipid-balanced skin repair cream for dry skin and inflammatory dermatosis

Optimal skin barrier function is dependent, in part, on the absolute and relative proportions of lipids (ceramides, free fatty acids, and cholesterol) in the skin. Ceramides are an essential component of the skin lipid barrier, and comprise 45% of the stratum corneum lipid. Damage to the skin barrier can reduce ceramides and lipid content, leading to increased transepidermal water loss. Skin repair cream is a next-generation topical treatment that contains ceramide-3, cholesterol, and free fatty acids in a proprietary nanoparticle delivery technology. Skin repair cream, through the restoration of skin lipid balance, may be effective in rebuilding the damaged lipid barrier in patients with atopic dermatitis, allergic contact dermatitis, and irritant contact dermatitis. Indeed, studies have shown that balanced lipid mixtures are efficacious as monotherapy and in combination with topical steroids in improving skin barrier function in conditions such as contact dermatitis (Berardesca E, et al. Contact Dermatitis. 2001;45:280–285). These findings, along with the treatment-refractory nature of many dermatologic conditions, prompted the current clinical experience (case reports) with skin repair cream. In a pediatric patient who had received extensive prior therapy for atopic dermatitis, addition of skin repair cream to his current routine improved symptoms by 80% within 3 weeks. In a case involving a 48-year-old patient with keratoderma climactericum, treatment with skin repair cream resulted in impressive improvements in skin thickness at 2 weeks. Another patient with thickened skin on the soles of her feet (attributed to psoriasis) experienced marked improvement on treatment with skin repair cream and symptom flares on discontinuing treatment. In 3 patients with wrinkling beneath the eyes secondary to lax skin or blepharochalasis, treatment with skin repair cream reduced fine wrinkles at 4 weeks. Skin repair cream was well tolerated by all patients, with no complications reported. Additional case reports will be provided to supplement this clinical data, including before-and-after photographs. On the basis of early clinical experiences, the effectiveness and safety of this balanced lipid mixture warrant further evaluation.

Biochemical composition of the deep-sea red crab Chaceon quinquedens (Geryonidae): organic reserves of developing embryos and adults

Deep-sea red crabs Chaceon quinquedens (Smith) were collected in traps at depths of 860 and 1043 m in the northern Gulf of Mexico. Ovigerous crabs were maintained in the laboratory and the developing embryos were sampled every 2 wk until hatching. Proximate analysis (lipid, protein, carbohydrate, and ash) of embryos was performed to determine patterns and rates of organic reserve utilization during embryogenesis. Midgut gland, gonads, and clutch (as appropriate) of adult crabs (males, non-ovigerous females and ovigerous females) were analyzed for the same components as the embryos. Red crab embryos exhibited different patterns of yolk deposition and subsequent depletion of yolk components during embryogenesis. There was a range of lipid to protein (L:P) ratios among the different clutches examined, indicating plasticity in the relative proportions of lipid and protein yolk. The energy used for embryogenesis was estimated by converting the amounts of lipid, protein and carbohydrate in the embryos to their caloric equivalents; final values, taken from 9 mo-old embryos whose siblings were hatching as zoeae, were subtracted from the initial values of sibling embryos sampled at the time of collection (2 to 3 mo old). The amount of energy consumed during embryogenesis in the laboratory was relatively constant (0.12 to 0.13 cal egg-1). There was considerable variability among the concentrations of organic reserves in the midgut gland of adult crabs and in the ovaries of females. Variations in midgut gland L:P ratios and ovaries were related to the reproductive status of the females, but there were no trends related to depth of capture.

Abnormalities of Lipoprotein Metabolism in Patients with the Nephrotic Syndrome

Patients with the nephrotic syndrome characteristically have multiple abnormalities of lipoprotein metabolism, but the cause and exact nature of these abnormalities are uncertain. In this study, we measured serum lipids and apoproteins in 57 patients with the nephrotic syndrome. We also determined the kinetic indexes of low-density lipoprotein (LDL) metabolism in six patients, and again in three of the six after recovery. The patients with the nephrotic syndrome had elevated serum concentrations of cholesterol, triglycerides, and phospholipids, which were confined to the lipoproteins containing apoprotein B. The serum concentrations of high-density lipoproteins and the associated A-I and A-II apoproteins were similar in the patients with the nephrotic syndrome and normal subjects. The relative proportions of lipids and their positive association with the increased serum concentrations of apoproteins B, C-II, C-III, and E suggest quantitative rather than qualitative differences in the lipoproteins. All the patients had lipiduria, which probably reflected the excretion of high-density lipoproteins, although no intact immunoreactive apoprotein A-I was found in urine. Serum albumin concentrations were inversely related to serum lipid concentrations in the patients, the severity of the hypoalbuminemia corresponding to the degree of change in serum lipoprotein concentrations. The kinetic studies of lipoprotein metabolism revealed an overproduction of LDL apoprotein B that returned to normal after recovery. The elevated serum concentrations of LDL cholesterol, other lipids, and apoprotein B in patients with uncomplicated nephrotic syndrome are due to reversible increases in lipoprotein production.

Folded chromosomes of vegetative Bacillus subtilis : composition and properties

The isolation of folded DNA from Bacillus subtilis, a Gram positive bacterium is described. When the lysis was achieved with 1 M NaCl a slow sedimenting nucleoid was obtained (1600-2000 S). Conversely, when the lysis was achieved with 0.2 M NaCl a fast sedimenting nucleoid was obtained (3500-4000 S). The yield of folded DNA was between 80 to 90 % of the total lysate DNA. Both nucleoids contained the same amount of RNA, but the relative proportions of lipids and proteins were different. Folded chromosomes were prepared in the presence of spermidine: artifactual protein binding is shown to be unlikely. Electrophoresis of nucleoid proteins showed a dominant polypeptide (MW = 36,000), which remained associated with DNA after sarcosyl treatment and could be partially removed by heat mediated DNA unfolding. In vitro transcription by endogenous RNA polymerase bound to the fast sedimenting-nucleoid was rifamycin resistant; the template capacity of the fast sedimenting-nucleoid was compared with that of the completely unfolded chromosomes.

Lipoproteines seriques anormales dans l'hepatite virale cholostatique

1. 1. In serum from patients suffering persistent viral hepatitis with total biliary obstruction, abnormal lipoproteins which characterizes cholestasis are separated by centrifugation and gel filtration. 2. 2. The relative proportions of lipid and protein components are different from those of the abnormal lipoproteins already studied in other cases of cholestasis and are characterized by a higher protein ratio (20% of the micellar weight). Cholesterol is the major constituent of those abnormal lipoproteins. 90% of total cholesterol is in unesterified form. Phospholipids represent 31% of the micellar weight. 3. 3. Those abnormal lipoproteins show the same immunological properties as abnormal lipoproteins previously separated, as well as the same antigenicity revealed by specific immune serum before delipidation and the same antigenic characteristics after delipidation, caused by the presence of A and C apolipopeptides and albumin. This latter component represents only 10 to 15% of the protein moiety. 4. 4. These results are in favor of abnormal lipoprotein plurality. The occurrence of at least two variants of abnormal lipoproteins has been established by using the same fractionation procedure. 5. 5. The presence of abnormal lipoproteins in the serum of patients with cholestatic viral hepatitis is associated with an important decrease not only in the amount of α-lipoproteins but also in the amount of β-lipoproteins. These abnormalities showed the impaired synthesis of lipoproteins in these hepatic patients.